leader. the military says the secondary explosions are proof of explosives stored in the building. hamas is claiming its own trophy. the group's military wing says it has shot down a military f-16 and damaged two other israeli aircraft. israel denies losing any aircraft. egypt is trying to stop this war before it is too late. cairo's intelligence chief is spearheading talks to end the violence. but on the border, peace looks like an unlikely prospect. our senior international correspondent, ben wedeman joins us now between the border between israel and gaza. ben, ground war, are we about to witness that? >> reporter: i don't think immediately, don. i think there's still time needed to get the israeli military ready for a ground invasion. keep in mind that gaza is an area just twice the size of washington, d.c., with a population of 1.5 million people. any military force that goes in there has got to contend with the possibility of a lot of civilian casualties and a fair amount of resistance, from hamas fighters. now, what we're seeing here on the border are intense preparations, all night long. we've been watching as big trucks carrying tanks, carrying armored personnel carriers have been going up and down the road. a lot of soldiers in this area. the israeli government has yet to say when or if they would finally make a decision regarding a ground invasion into gaza. and at the same time, as you've mentioned, there are intense efforts underway by the egyptians, among others, to try to head off a possibility of an escalation of a conflict, that already has nerves rattled on both sides of the border. don? >> ben, when last we spoke to you, it seems like each time we spoke to you, you heard explosions in the background. are you still hearing that? >> reporter: yeah, if you'd come to us about two minutes earlier, you would have heard several large explosions. and those have been going on, on a fairly regular basis, all evening long. we see these great big balls of flame coming from gaza city, which is actually just right behind me. we're also hearing that israeli warships off the coast are also bombarding the coastal area, as well. so, yeah, i just heard a big blast behind me and another one now. so it's -- there's no respite in this bombardment of gaza. >> ben wedeman, stay safe with you. stay safe for your reporting. meanwhile, israel is mobilizing 30,000 troops. who will wait for the word to cross the gaza border and turn this conflict into a ground war? last time we saw was four years ago, operation cast iron. a grueling three-week campaign. and the numbers from that war are striking. 13 israelis killed versus 1,400 palestinians who died. for now, all the people in gaza can do is listen for the missiles, watch the border, and hope for the best. cnn's sara sidner is there with them. >> reporter: today, just like the last few days, we've been hearing a chorus of drones overhead, and a symphony of air strikes. we've also seen plenty of rocket fire coming out of gaza, towards israel. weapon witnessed several times, several rockets at a time, heading over towards israel. also, we need to tell you about what's going on with the potential cease-fire. we were hearing from the arab league that they were perhaps in negotiations between gaza and israel, but israeli officials are denying that there is talk of a cease fire, that they're involved in, anyway. we do know that we're expecting a delegation coming over from several countries, out of the meeting that they had in cairo, to show up here in gaza, perhaps tomorrow. we were waiting, also, to hear what is going to happen when it comes to the ground troops, that israel has amassed on the border. now, right now we're hearing the sounds of planes, and that usually only means one thing, that there will be air strikes that follow. and it's this time of night and into the wee hours of the morning that usually things get very, very intense, with lots of blasts of air strikes. but also we know that there have been some blasts coming from the israeli ships in the sea. we, ourselves, experienceded some of the loud booms and bangs that were coming from the sea. we were right on the water there. so a lot of concern. the civilians are not in the streets. most people have hunkered down in their homes. most of the businesses have been closed. we know that more people have been killed here, including militants and civilians. and many people have been injured today. sara sidner, cnn, gaza city. >> sara, thank you very much. israel and hamas are on the verge of an all-out ground war. is it too late to turn back now? michael orn joins us now. "the washington post" is reporting that israeli air strikes also targeted police headquarters, a police headquarters building. is israel trying to topple gaza's government by destroying its basic physical infrastructure? >> well, tonight there are about 5 1/2 million israelis under rocket fire, don. 5 1/2 million israelis who are either in bomb shelters or afraid to go more than a 15-second run from the nearest bomb shelter. our goal is very simple. it's to restore security, safety, to all of those 5.5 million members of our population. that's well over half of our entire population. and we are trying to drive home a message to hamas that they cannot shoot at israeli civilians, try to kill israeli civilians with impunity. >> listen, i know that you're the israeli ambassador, but there are also palestinians, too, who are in danger of being killed as well. >> well, we deeply regret any loss of civilian life or any injuries incurred by civilians on the palestinian side. we take super human measures to avoid that to the greatest degree, if possible. we have this computer that makes tens of thousands of phone calls and sends text messages to people in areas that are going to be struck by israeli war planes, so they can get out of those areas safely. and we've been able to reduce, to a remarkable extent, the amount of civilian casualties, on their side. now, compare that to what hamas is doing to us. they're trying to maximize the number of israeli civilians that they kill. that's the difference between a terrorist organization and a democratic country. we invest in bomb shelters, they invest in bombs. completely different story on the gaza side. mr. ambassador, last night you told our piers morgan that israel was still allowing humanitarian aid to flow into gaza and even letting gazans go to israeli hospitals. is that still the case? >> it is. in fact, the number of gazans that were let out of the gaza strip into israeli hospitals increased significantly today. >> at this point, can a ground war be avoided for israel? what is the trigger here, the point at which it's too late to turn back? >> well, we certainly hope so. but it really is up to hamas. if hamas continues to escalate, continues to keep 5.5 million israelis under rocket fire, that's an intolerable situation for any country, anywhere in the world. and israel will take all necessary and legitimate measures to defend its citizens, including ground operations. >> i have to run here, but i think it's a fair question that i want to ask you. i was speaking to our very own jim clancy yesterday, who has covered this region since the 1980s. i'm not sure if you're aware of the conversation, but he said, essentially, that the strategy that israel is using at this point is antiquated, and it just keeps the region spiraling out of control. and that something must be done. some sort of negotiation. what do you make of that? >> well, we're dealing with hamas here. hamas is an organization whose covenant calls for the destruction of the state of israel. it actually calls for the destruction of the jewish people anywhere in the world, including the united states of america. it's a genocidal organization. it doesn't request our legitimacy, our right to exist, and it's not looking to negotiate with us. so i would ask tom respectively, imagine that he is the prime minister of israel, he wakes up tomorrow morning, and he's got what we've had in the last few months, 8,000 rockets falling on half the population of the country. what else can we do, other than to take all legitimate necessary messages to defend ourselves. we wish it was otherwise. we wish there was a government in gaza that cared about its civilians the way we care about our civilians, that was investing in education, investing in hospitals, instead of investing in the 12,000 rockets that they have in their arsenal. we live in a tough neighborhood. and we have to live up to that reality, but you should know that the people in the government, the state of israel, want peace with their neighbors. and we're willing to just sit down and negotiate with them, if their willing to sit down and negotiate with us, everything's on the table. we sign on to the two-state solution. we're committed to it. just stop shooting at us. >> all right. israeli ambassador, michael orn, thank you very much. we appreciate your time. >> thank you, don. what would happen if there is a ground war in gaza? we'll continue the discussion on the israeli/palestinian conflict. and former nfl linebacker chris draft lost his wife to lung cancer. he'll join us live with the emotional story and a message of hope for others battling the disease. splash with the employ. 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landing in thailand in the next few hours. he is on a three-day journey to asia, where he'll attend the east asia summit. the president will also stop in cambodia and myanmar. his visit to myanmar, the former burma, will be the first-ever stop there for an american president. the so-called fiscal cliff just 45 days away. president obama and congress must cut a deal, otherwise, massive tax hikes and spending cuts will kick in january 1st. democrats and republicans seem more in the mood to compromise after a series of meetings. >> i know these challenges won't be easy to solve. but we can do it if we work together. that's why on friday, i sat down with congressional leaders to discuss how we can reduce our deficit in a way that strengthens our economy and protects our middle class. it was a constructive meeting and everyone agreed that while we may have our differences, we need to come together, find solutions, and take action as soon as possible. >> for too long, partisan bickering has paralyzed washington, preventing members of both parties from reaching across the aisle to find common ground. that must stop. washington can't keep ducking the tough decisions. and the fiscal cliff we're headed toward provides an opportunity for both parties to change our country's irresponsible spending path. >> both sides may have to give ground to get a deal. the white house and democrats have pushed for increasing income tax rates on the wealthy. republicans have preferred to focus on closing tax loopholes and eliminating deductions and tax credits. coast guard patrol boats and helicopters still searching a 1400-square mile section for the gulf of mexico for two missing oil workers. they haven't been seen since friday, when an explosion tore through the oil platform where they were working. 11 workers were hurt in the blast. a spokesman for black elk energy, which runs the platform, says the fire is out. federal authorities are investigating the cause of that. nfl legend mike ditka has suffered what's been called a mild stroke. the former coach and hall of flame player told the "chicago tribune" he feels good and it's not a big deal. ditka is currently an espn analyst and will not work any nfl shows this weekend, but he's expected to be back on the air soon. get better. israeli troops are massing near the gaza border. and if they push forward, experts say it could be a bloodbath. we'll explain why after the break. ♪ [ male announcer ] you build a reputation by not breaking down. consider the silverado 1500 -- still the most dependable, longest-lasting full-size pickups on the road. and now we've also been recognized for lowest total cost of ownership -- based on important things, like depreciation, fuel, and maintenance costs. and now trade up to get a 2012 chevy silverado all-star edition with a total value of $9,000. from outstanding value to standing the test of time, chevy runs deep. air raid sirens wailed in tel aviv, warning crowds of panicked people to take cover, because a rocket attack might be seconds away. families huddled by their cars, bracing for a potential hit. israel's military says its iron dome missile defense system has blocked rockets headed for the city. since the attacks began on wednesday, at least 46 people have been killed in gaza. three people have been killed in israel. if israel launches a ground attack in gaza, experts say the battle could be as bloody as a 2008 invasion that killed 1,400 palestinians or worse. since then, hamas has got been were the weapons and its foot soldiers are better trained. cnn's brian todd explores what a ground war in inner city goza might look like. >> reporter: a precision strike from the air, killing the chief of hamas' military wing. but it appears israel is getting ready to go beyond pinpoint hits like this to contain the hamas threat. an israeli official says the army has already moved nearly a division's worth of troops, as many as 2,000, to the border of gaza. israel sealed off the main roads around gaza. will israel invade on the ground? >> i think the chances are going up. >> reporter: jeffrey white, a former analyst with the defense intelligence agency, says an israeli ground invasion of gaza would be a brutal, bloody grind. >> there's a pretty high density of population throughout the strip. it's highest in the major areas, rafa, gaza city, but there are a lot of civilians in other places as well. the other part of this is hamas fights from inside the cities. >> reporter: cities of narrow streets, bazaars, apartment buildings. translation, a punishing building-to-building slog, in a place that's slightly twice the size of washington, d.c. we used a google map with cnn contributor, james spyder marcus. >> what kind of combat are we talking about here? >> this is called combat in restricted terrain. and clearly what we have here in gaza city, there are about 500,000 people that live in this city. and you can only imagine the type of combat that's got to take place in this very restricted terrain. >> reporter: terrain where mark says israeli troops will be exposed to ambush, sniper fire, suicide bombings. if a ground invasion is launched, analysts say it could be eerily similar to a conflict four years ago, after a series of hamas rocket attacks on israel. in late 2008/early 2009, israel launched operation cast let, a short period of air strikes followed by a longer ground invasion of gaza. these are scenes from it, entire apartment blocks destroyed. estimates are up to 1,400 palestinians were killed. many of them, civilians. >> reporter: about a dozen israelis were killed in that operation. then the israelis were able to split up gaza, cut supply lines. this time analysts say hamas could make it tougher. >> they have some better weapons, no question about it. they've got much better anti-tank capability, you know, with the russian atgm. they have a better s.a.m. capability. >> white says in 2008/2009, hamas units were not good at close combat with the israelis. he says they broke and ran, didn't coordinate well. he says since then, they've made an effort to improve that with iran's help. brian todd, cnn, washington. when congress convenes in january, it could be much of the same old, same old, unfortunately. ahead, we'll talk with one expert to find out if there's any hope for congress to make progress on the key issues this time around. music is a universal language. but when i was in an accident... i was worried the health care system spoke a language all its own with unitedhealthcare, i got help that fit my life. information on my phone. connection to doctors who get where i'm from. and tools to estimate what my care may cost. so i never missed a beat. we're more than 78,000 people looking out for more than 70 million americans. that's health in numbers. unitedhealthcare. ♪ [ male announcer ] this is karen and jeremiah. they don't know it yet, but they're gonna fall in love, get married, have a couple of 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