attack. over the next hour, cnn's sara sidner brings us "the whole story" on hamas, from how they were formed, what their ideology is, and how they've evolved over the decades. we want to warn you some of the images you'll see in this hour may be disturbing. >> pure, unadulterated evil. >> i can't even try to comprehend these monsters. >> terrorists. >> this is not islam. >> they should be spit out. >> we cannot expect that israel will continue to blockade gaza, deprive them of their freedom, and assume that at some point they will not resist. at some point, it's going to boil over. >> october 7th was different. october 7th changed everything. >> what happened on october 7th was absolutely unprecedented. hamas has certainly targeted israeli civilians before. that's not new. what is new is simply the scale and just the ruthlessness. >> how do you define hamas? who and what is hamas? >> hamas primarily is a social, religious, political movement. >> hamas is seen by most palestinians as a part of their social fabric. there are plenty of palestinians who cannot stand hamas, but they recognize that some of their neighbors, some of their family members are hamas supporters. hamas has several different aspects to it. it certainly does have a military wing, but it also has a political wing. it has social services. it sees itself as a movement. it calls itself the islamic movement. >> hamas is a nationalist movement that's committed to the notion of armed struggle for the liberation of palestine. out of all the different palestinian factions that exist, hamas is the only party that has an organized military, and a very well-resourced military force. so what that means is for many palestinians, hamas is the only party that can actually defend palestinian civilians against israeli aggression. >> that's the reality. that is how many palestinians view and consider them. a line of defense. >> reporter: since 2007, hamas has governed the gaza strip, a 25-mile-long, 7-mile-wide stretch of land with more than 2 million people largely cut off from the world by an israeli blockade. an area humanitarian rights groups have called an open-air prison. but the rise of hamas and what led up to its massacre of more than a thousand men, women, and children in israel is a story that begins long before hamas ever existed. >> this did not start on october 7th. >> reinforcements disembarked. >> the mandate said a couple things. it said, you should prepare this territory for independence, but you should also facilitate a jewish national home. >> the british tried various mechanisms to make them agree on some kind of settlement. >> and the british found they couldn't do both, so they gave up. they just left after world war ii, and they handed the problem over to the u.n. and said, we can't deal with it. >> the palestine problem moves into another stage of discussion. >> the u.n. sets up a commission that comes to the conclusion that the best solution here is to take this land and to divide it. roughly speaking, half to the palestinians, half to the israelis. the jews accept that deal. the arabs do not. >> and so war broke out. >> arabs and jewish nationals fought each other bitterly and relentlessly. >> as a result of that war, the state of israel declared itself and took control not simply of the territory that the u.n. had allotted to it, but some other territory as well, a lot of which had significant palestinian population. >> the new jewish state, israel, was born in a bath of blood. >> the birth of the state of israel for palestinians is called -- which means the catastrophe, because in order to pave the way to establish israel as a jewish state, there needed to be a mass ethnic cleansing of lestinians. more than 700,000 palestinians fled outside of the land of palestine, and palestine was essentially decimated. >> arab captives are held for evacuation. >> israel said essentially, we're not allowing them to return. so you may have thought you were leaving for a week, but you're never coming back. >> reporter: by the end of 1948, a newly formed israel had claimed 78% of the land of historic palestine. the palestinians, who hadn't fled to neighboring countries, settled in the remaining 22% of land that israel had yet to conquer. >> what is left is the west bank and gaza. so the egyptians control gaza. the jordanians control the west bank. and that's how it was until the 1967 war, when arab armies amassed on israel's border. >> the frontier of the gaza strip just a mere kilometer away. >> 1967 is one of the biggest historic moments in the middle . israel launches a surprise attack against egypt. >> the israeli forces have routed the armed might of their arab neighbors. >> the israelis conquer the west bank and gaza, and this is a moment of great exhilaration in israel because they feel as though they have defeated the arab armies in an extraordinary military success. they have not figured out what they're going to do with the millions of palestinians on that land. >> reporter: after the six-day war, the millions who fled to gaza and the west bank in 1948 are officially under israeli occupation. >> which left all these people in gaza and west bank citizens of nowhere. they weren't citizens of the israeli state, and so they were just stuck. >> palestinians begin to say, we need to liberate ourselves. >> reporter: throughout the '70s and '80s, bursts of violence between palestinians and israelis were commonplace. the palestinian liberation organization, which is formally recognized by the world, was led by yasir arafat, who was operating in exile outside the palestinian territories. but inside israeli-occupied gaza, a new resistance movement was under way. >> one of the biggest mobilization of palestinian civil society and actors against the military occupation. and the idea was they would disrupt the occupation apparatus. so they refused to open shops. they blocked highways. they refused to give tax. it was a period of significant agitation. >> reporter: around the same time, islamists within gaza and the west bank were shifting focus to a more aggressive approach towards their israeli occupiers. and a new armed resistance group would emerge, officially known as hamas . >> he was a spirititual leader the gaza strip and was one of the earliest founders and leaders of the muslim brotherhood chapters in palestine. and when hamas was established in 1987, he emerged as the leader of the movement, and in some ways the spiritual guide of the movement. >> reporter: unlike the secular palestinian resistance, the newly established hamas was not interested in liberating gaza and the west bank alone. instead, it set out to eliminate the state of israel altogether as outlined in its 1988 charter, a goal that made hamas an outsider to any peace negotiations, including the oslo accords. >> the oslo accords really set off earthquakes in both palestinian and israeli society. >> as our walls have been l long -- >> what the oslo accords ultimately resulted in was that the plo recognized the state of israel and so considered 78% of the land of historic palestine, and in return, the israeli government recognized the plo as the sole legitimate representative of the palestinian people. there was jubilation globally, and many palestinians, despite this historic concession, believed that this might pave the way to the establishment of a state on 22% of their land. but this was by no means noncontroversial or unchallenged. and for hamas specifically, this was something that they were fundamentally opposed to. >> those negotiations never really got off the ground. one of the reasons was this upsurge of violence. >> reporter: one of the deadliest attacks to derail peace came in february of 1994, just months after the signing and historic white house photo op. >> a jewish settler entered the mosque while muslims were worshipping there. the dozens of dead and scores of injured were rushed to hospitals in nearby towns. >> that was a turning point because hamas then decided to begin employing suicide bombing as a form of resistance. >> reporter: 41 days after the mosque attack, hamas responded, detonating its first lethal suicide attack, killing seven israelis at a bus stop. >> the big reason oslo failed was violence. the perception on both sides is that their adversary is not serious. israelis say arafat is not completely stopping terrorism. palestinians say the israelis are dragging their feet on a pullout. they're increasing settlement building even as they're making promises that they're going to read. >> the fundamental reason hamas has gained strength is that the palestinian authority, which is their competition, has been seen as feckless, corrupt, and unable to deliver on its core promise, which was a palestinian state. >> reporter: but to the west, hamas was not a negotiate partner. instead, it became a threat. in 1997, the u.s. officially designated hamas a foreign terrorist organization. >> if you protest nonviolently and so on, you are shot at. you are imprisoned. so they left only one avenue actually, which is armed resistance. >> hamas has decided that it is going to use violence, and it's going to use violence against civilians. it is going to be brutal. >> reporter: over the next decade, hamas continued its violence, and it would meet more violence in return. will they go home with a deal? . the latest from camp david. >> this wooded maryland retreat of u.s. presidents, camp david, was the site of a potentially historic summit in the summer of 2000. >> you had yasir arafat, the legendary leader of the palestinian liberation organization, who had a lot of credibility withth palesestinia. you had ahugugh barack, very distinguished israeli military figure, now prime minister. and you had bill clinton. >> reporter: their goal, end decades of hostilities, forge a palestinian/israeli peace e accord. >> if theyey cannot t make pror now,w, there will be more hostility and more bitterness. >> it seemed as though they had kind of come to an agreement, and then arafat pulls out at the last minute, best we can tell, because he believed that if he did this, hahamas would gainin power. >> so the israeli story on camp david is that the israeli prime minister offered significant concessions, and the palestinians said no. the palestinian view was that they were set upup at camp d da thatat israel and d the ununite ststates made e offers they kne that yasir arafat could not accept, and as a result, they were made to look bad. >> reporter: just two months after those talks failed to get an agreement, a former israeli defense minister, who many arabs called the butcher of beirut for israel's 1982 invasion of lebanon, made a provocative, heavily guarded visit to the temple mount. a holy site in christianity, judaism, and islam. it is also a flashpoint of contention over who should control it, israelis or arabs. >> the violence that observers believe to be inevitable erupted. >> reporter: just the first sparks of what became the second intifada, a violent and deadly conflict between israelis and palestinians over israeli occupation of the west bank and gaza. the second intifada would last nearly five years. a half-decade fight in which hamas became known for their routine use of both terror and destruction. >> over time, more and more of israel came into range as hamas' weapons got better and better. also the number of missiles and rocketed increased. >> reporter: israeli forces demolished over 4,000 palestinian homes and arrested thousands. israel shut down and bombed ministries and infrastructure, trying to coerce palestinian leaders to end the violence. between 2000 and 2005, there were over 4,300 registered fatalities with a palestinian-to-israeli ratio of just over 3 to 1. finally in february 2005 came this announcement from the palestinian authority and israel. >> we have agreed with the prime minister, ariel sharon, to cease all acts of violence. >> reporter: later that year, israel unilaterally implementing its so-called disengagement plan to evacuate israel settlements and military posts from gaza and a section of the west bank. thousands of settlement residents s lost their homomes.. >> it was both a physicacal l b alalso a psychologogical disengagemement on behalf of th israelis from gaza. it was no longer their problem. >> that was a very, very difficult, painful step for israel to take, to pull settlers out. and how did palestinians responond? by shooting rocketets. and therere's some t truth to t. it's also o true, thoughgh, tha whwhen israel pulllled out o of it c continued to envelop it in blockade. >> reporter: a blockade to isolate hamas and attempt to prevent smuggling of weapons. but it also severely limited the transport of basic necessities for palelestinian cicitizens i gaza. > the b blockade was quite horrifific. therere was an immedediate coll inin the qualility of life in g. medicines,s, food items, watere alall of the itetems of a norma life were immediately suspended. and the immedidiate impapact wa signgnificant inincrease in n p and destitutution. > the yeaears d directly afa israeli disesengagement from ga in 2005 leleading up t to the palestiniaian elelections in 20 saw an unprecedented wave of violence. i remember being in the city where i was raising my young son and feeling unsafe to simply go out about my daily life in the streets. >> reporter: and from gaza, hamas continued to terrororize israrael. >> s so israelel was operatitinr the assumpmption despite 2 2 min palestiniaians being i imprison it couould still e expect cacal. what hamamas was doing w was du ththis period,d, shahattering t illusion. every few months, if not years, it would fire rockets in order to force israel to reconsider. >> reporter: in 2006, nearly a year after the announcement of the cease-fire, elections for the palestinian legislative council were held in gaza. >> this feted and smelly bleak tunnel. >> repororter: cnn cororrespond christiane amanpour covered it and its aftermath. >> it's very clear that election was insisted on by the administration of george w. bush and d condoleezzzza rice andnd group ofof a americans w who be that the iraq war r of 2003 3 w bring g democracy y to the widi middlele east. this w was a v very flawed assumption, and the americans insisted on this election even though the israelis and the palestinian authorority, t the legigitimately, , internatioion accecepted and recogninized palestininian authorority, wara the uniteded states nonot toto this electction gogo a ahead be they feared the hamas would prevail. and that is exactly what happened. >> reporter: the hamas victory was resounding, winning 76 of 132 seats in the legislature. shocking results for the u.s. and israeli officials, bringing to power a group the united states had designated as a terrorist organization. but a group that had been making a difference in the lives of everyday palestinians. >> for many palestinians, hamas is a lifeline. for two decades, they've built a grassroots network of affordable social services, like this medical clinic that charges $2 a visit. >> t they y provided e educatio. they werere very welell entrenc with the citizens and civilians. so that is one of the reasons why hamas s won in gazaza in 20. >> so afteter the e 2006 electc and hamas victctory, there are questitions on thehe scope of f' power. isis it still undeder the palestiniaian authoritity, or r independent? and there are questions about who runs particular parts of gaza. hamas is worried that there will be a coup. as a result, it effectively does a coup. >> reporter: the coup in 2007 known as the battle of gaza was relatively brief, bloody, and left no doubt that hamas was not a part of the palestinian authority, which governed the west bank. hamas was a much more extreme and violent group, now solely in charge of gaza. >> it seizes power in gaza in 2007, and it violently goes after the individuals associated with the palestinian authority. rrested, tortured. >> but one thing is clear. hamas managed to do what fattah was unable to do prior to 2005, whicich is to sesecure the stre in gaza, to put an end to the rampant lawlessness that we were seeing. >> reporter: having hamas in charge of gaza meant the blockade w would continue. >> so the cutoff of goods going in and out of gaza have a big impact on hamas. they make it hard for hamas to provide any prosperity to ordinary gazans. >> i visited gaza in 2012. you might have power for a couple of hours a day, and these conditions were getting worse and worse e and worse. insiside the gazaza strip,p, has not a popopular movemement. there'e's no e elections. ththere's no w way to get rid o them or anything like that. so people in the gaza strip just lived with them. >> reporter: and the conflict between israel and hamas would not abate. hamas attacking israel -- >> that was the explosion. we just heard one explosion going off. i think it came from that direction over there. >> reporter: israel firing on gaza. >> if you look to your left, destruction. >> reporter: i reported from both gaza and israel, telling stories of destruction and dismay. >> around 3:30 this morning here in gaza city, a massive explosion. we know there have been at least four bombardments. >> reporter: and it would only escalate in 2014 after the israel security agency identified hamas members as responsible for the kidnapping and killing of three israeli teenagers from a jewish settlement in the west bank. and weeks later, the abduction and murder of a palestinian teen, whose body was found in jerusalem. outrage and anger on both sides would not be contained, erupting in the 2014 gaza war. >> israel put togethther an operation n which consisted of ababout t 50 days with 70,000 israeli call-ups for the defense forces. they went into gazaza, and on n three didifferent axeses, on th nortrth and the e center a and south, it resusulted in 66 israi deaths of soldiers, 6 israeli citizens. the u.n. estimates 2,100 palestinian and hamas s deaths during that same operation.. it was after that that the israeli government really started taking a different look at hamas and what they were doing in the gaza strip. c'mon, we're right there. c'mon baby. it's the only we need. go, go, go, go! ah! touchdown baby! -touchdown! are your neighbors watching the same game? yeah, my 5g home internet delays the game a bit. but you get used to it. try these. they're noise cancelling earmuffs. i stole them from an airport. it's always something with you, man. great! solid! -greek salad? exactly! don't delay the game with verizon or t-mobile 5g home internet. catch it on the xfinity 10g network. more than 2,100 palestinians were killed. more than 60 israeli soldiers were killed. >> going in in 2014 into gaza after that sustained bombing, you just had this huge sense of the utter scale of the destruction. it was really hard, near impossible to find anyone who genuinely supported what hamas had done. >> "i hope god won't let anyone taste our suffering," this woman in gaza said. >> in n the west bank where the majority of palestinians live, the year 2021 was a very bloody year. >> a flashpoint has definitely been the possible eviction of some palestinian families, some of which have been living there for generations. >> reporter: according to the u.n., since prime minister benjamin netanyahu's re-election in 2009, there were over 14,000 instances where palestinians were forcibly removed from their land by israeli settlers. this includes east jerusalem. >> there are sirens going off all around jerusalem right now. this usually means that there is the potential of rockets coming in. >> in 202021 was the firirst ti ththat the palalestinians mobil as a single e peopople, demandi single thing, which is to dismantle israel's regime of apartheid. and for hamas, it becomes the military power t