Im wolf blitzer. Youre in the situation room. Lets get to the breaking news. Prosecutors now say the knifewielding man shot dead by Boston Police plotted with others to Kill Police Officers in massachusetts this week. And they say there was a separate plan to behead someone in another state. Another suspect now in custody, that suspect made a Court Appearance today. Officials have said the dead man was radicalized by isis and theres also now a new warning from the fbi about the ability of isis to influence lone attackers through encrypted online messages and social media. Ill speak about that and more with the Foreign RelationsCommittee Chairman senator bob corker as well as our correspondents analysts and guests. Were all watching. As we stand by for full coverage. Lets begin with our justice correspondent, pamela brown, shes in boston with the very latest. Pamela . Reporter wolf disturbing details coming from these Court Documents detailing the plots that the suspect killed yesterday, usaama rahim, had talked about with another person arrested by the fbi, david wright who appeared in court today, and a third person in rhode island. According to the fbi, usaama rahim, wright and another person met on a beach in rhode island in late may and talked about plans to behead another victim in a separate state. So there had been talks to behead someone. After that we learned that yesterday morning, according to the fbi in wiretapped conversations, rahim called wright and said he wanted to change plans and move the day up, that he couldnt wait and that he wanted to go over the boys in blue and attack and Kill Police Officers. People ive been talking to say that the idea that he wanted to behead someone before indicates perhaps he wanted to do the same to Police Officers. So officials that weve been speaking to believe he was an imminent threat. Hed recently purchased three knives. Heres what the Police Commissioner in boston had to say about him. This guy required 24 7 surveillance. So we thought the threat was severe enough that we had to approach him. We never expected what happened. But hopefully it will all come out later so theres a better understanding of the level of threat. But i cant go into anything more than it was a very serious threat and thats why we didnt take it lightly. Reporter federal authorities have been investing usaama rahim for at least a couple of years. Its unclear when he was put under 24 7 surveillance. David wright his associate, faces a charge of conspiracy to destroy evidence to impede an investigation. That evidence was rahims smartphone after rahim allegedly told him about his plan to kill officers yesterday or today. Wolf . Is there a third suspect out there as well or others involved based on what youre hearing . Reporter what im hearing from Law Enforcement officials ive been speaking with is they raided that third suspects home in rhode island. It was in direct connection with this network that were talking about. But that a third arrest has not been made. As we speak, authorities are trying to build a case. Pamela brown in boston, well get back to you. Theres growing concern that isis is able to influence and activate lone attackers here in this country through its sophisticated use of social media and its use of encrypted messages proving especially worrisome to u. S. Counterterrorism officials asking congress for help right now. Lets go to jim sciutto whos getting new information. With these cases in boston, the shooting in texas last month, you get a real sense of deep, deep concern from counterterror officials. We heard the fbi in effect pleading for help concerned that potential terrorists are using encrypted communication and they dont have the legal power to p sto it. Heres the fbis counterterror chief. Were past going dark in certain instances. We are dark. The ability to know what theyre saying in these encrypted communication situations is troubling. Whats key here is that u. S. Officials say contact on the web alone may be enough both to recruit, to train and to activate terrorists here on the homeland. The gunman killed in garland, texas, last month, the man shot by Law Enforcement in boston on tuesday, all believed to have been radicalized by isis all highlighting this threat. And isis tremendous social media prowess gives them unprecedented Digital Force multiplier. 2,000 core isis supporters pushing the message out. 50,000 people retweeting that message and more than 200,000 receiving and reading that message. The numbers in the u. S. Also concerning. The fbi says hundreds perhaps thousands. The challenge for Law Enforcement is distinguishing between lukewarm supporters and potential terrorists. What you heard from the fbi today is theyre taking no chances. And this case in boston is an example of that. Once they have an intercepted phone call saying they were ready to go the victim of the shooting saying he couldnt wait, thats when they moved in. Thats the kind of thing theyre doing more. In texas, that was a case where he was on their radar screen. They didnt act and that was potentially a tragedy. I keep hearing from top u. S. Officials how baffled they are and pretty impressed that these isis sympathizers have this social media capability. No question. And weve seen it in their propaganda. Theyre great at advertising their atrocities. But being great at turning americans to terror purely from a distance and over the web, over the phone, et cetera thats truly concerning. They have enormous capabilities in that area as well. Jim sciutto, thank you. Joining us the chairman of the senate Foreign Relations committee, republican senator bob corker of tennessee. Mr. Chairman thanks very much for joining us. Wolf, always good to be with you. Thank you. You just heard jim sciuttos report the assistant director at the fbi for counterterrorism Michael Steinback saying there have been upwards of hundreds of americans traveling to join these terror groups. Whats the plan to stop this recruitment of americans . Wolf, that is huge question. Weve been concerned from day one about their ability, as youve been reporting right now, to recruit people through social media. Thats one of the reasons i think you saw this debate that took place on the floor over the last couple of weeks relative to the patriot act. We have tools in place that are not being utilized in their full capacity. We know that technology is changing such. Weve got to upgrade. But again to even lessen our abilities today to deal with some of these things to me is not appropriate. Thats not directly relatable to this social media piece. But it is one of the tools that weve been able to utilize to keep terrorist at bay. So back to the bigger picture, look this is something were going to be dealing with for a long long time. I dont think theres any question to americans now as they watch your reporting, as they see whats happening, that isis is a National Security threat. So we have both the issue of dealing with them on the ground in places like iraq and syria and libya and other places. But also how do we keep people from being influenced . Its very typical. And, again, one of the things we have to have is the very best tools at the nsa and other places to try to interdict and try to make sure even when theyre encrypted, we scale up and have the ability to intercept and keep bad things from happening here in our country. But this is going to be very complex, very difficult, especially when people dont even have to go to the places that isis exists on the ground to be turned in such a way to want to turn on americans. This 26yearold terror suspect who brandished a big knife, usaama rahim, in boston he was shot by fbi and police. Were showing a picture of that militarystyle knife that he had. The plan according to court papers for him was to randomly kill in their words, Police Officers in massachusetts on june 2nd or june 3rd today and yesterday, and then to go to another state and behead someone and supposedly this usaama rahim was radicalized by isisinspired social media messages. Heres the question is this just some random incident or is more of this out there potentially . Wolf i think theres no question that were concerned that more of it is out there. You have people in this country that obviously feel disassociated from society, they have issues theyre attracted youve seen some of the publications that have been put out. I looked at one in the cloak room while we were debating the patriot act. These things are done in a very professional way. These people i hate to say, have a lot of talent in reaching people. So again, theres multiple ways that people can be radicalized. But i think the one that should concern americans the most is the route youre talking about right now. Just through a social media site you take someone whos unhappy with their state in life for whatever reason and they feel like theyre a part of a greater cause unfortunately, a cause that to me is certainly a terrible cause. And they commit these random acts. And weve seen messages going out. Youve read them trying to engage lots of people in random acts around our country to disrupt our society. And thats what were dealing with here. Senator, i want you to stand by. We have more to discuss involving isis whats going on in iraq iran a lot more with the chairman of the senate Foreign Relations committee when we come back. Hey, what are you doing . You said you were going to find out about plenti, the new rewards program. I did. 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Right now, buy an eligible printer and get three months of free ink with hp instant ink. Available at participating retailers. The most affordable way to print. Hp instant ink. Were back with senator bob corker chairman of the senate Foreign Relations committee. Senator, i want you to stand by for just a moment. Were just learning that israels military says two rockets were launched from gaza into southern israel. Sirens sounded in two israeli cities. No injuries were reported. This is the second instance of rocket fire reported by israel in a week coming in from gaza. Well check that out. Whats going on over there. Meanwhile, another controversy is brewing over Irans Nuclear program as the clock keeps on ticking on a proposed nuclear deal. Lets bring in our Global Affairs correspondent, elise labott, shes working the story. There are new developments here as well. That june 30th deadline is looming and new claims that iran could be reneging on its promises are posing a potential embarrassment for the Obama Administration. But now the state department is calling these accusations absurd and is fighting back. Less than a month before the deadline for a nuclear deal with iran new questions about whether iran can be trusted to abandon its stockpile of nuclear fuel that can be used for a bomb. Even as the president told in an Israeli Television program, iran is on track to get rid of it. The very stockpiles that president netanyahu went before the United Nations with his picture of the bomb and said that was proof of how dangerous this was, all that stockpile is gone. Reporter under the Current Interim agreement with world powers iran must freeze its nuclear activity. The deal on the table requires iran to reduce its stockpiled nuclear fuel by 96 . But a new report from the iaea the u. N. s nuclear watchdog, found irans stockpile had actually increased by 20 in the last 18 months. In the past the iaea has reported theyve gone up and theyve gone down and always met their requirements. Reporter the issue has exploded online after the New York Times reported quote, western officials and experts cannot quite figure out why irans stockpile continues to grow. The state departments marie harf shot back on twitter, not true. Neither harf said was the claim the stockpile poses a major diplomatic and political challenge to a deal. Its not one of the big outstanding issues. Its an outstanding one but its not by any means one of the toughest and not a major obstacle inside room. Reporter whatever the reason for these socalled fluctuations iran will still need to get rid of nine tons of fis fissile material. They said the Obama Administration is naive. But many National Security experts say the stockpile issue should not hinder an agreement. Well see what happens. Thanks very much. I want to get the reaction from the chairman of the senate Foreign Relations committee, republican senator bob corker of tennessee is still with us. I know youve watched this debate unfold. Where do you stand on whos right . Would it be the New York Times report or the state department and marie harf . Let me start by saying theres no question that iran cannot be trusted. I think thats universally felt. I think there are people on either side of the aisle that believe that iran can be trusted. So this is not a trust but verify type of arrangement. It should be solely verify, verify, verify. Theres no question that their stockpile has increased. Thats not debatable. And what i hope is going to happen they do have to get down to 300 kilograms as part of the agreement. I guess the question is, wolf are they doing this to put themselves in a better negotiating position by growing this stockpile while the negotiations are under way or are they not going to live by it . We dont know. But i hope there will be no sanctions alleviated until they get down to that 300 kilogram stockpile. The problem is when the person said this is not an issue, this can be dealt with, i would like to know how. They dont have a conversion facility to downblend or downgrade or to do what they need to do with the 5 . So are they going to ship it out of the country . Those are issues that need to be dealt with and hopefully will be dealt with and hopefully we havent seen the final agreement. It will be in a very blackandwhite, explicit way that they have to deal with this. But they have to get down to 300 kilograms per the political agreement that was reached on april 2nd. I know that youve suggested that there was some sort of Administration Document out there that has the outlines of an agreement with iran and what would happen after year ten, this is supposed to be a tenyear deal. You say the administration is refusing to share that document. Whats going on here . So if you read the political agreement that was achieved on april the 2nd theres reference to something called the Iranian Nuclear development program. Its not capitalized. But theres a document that explains what iran is able to do per the agreement after the tenyear period. You also may remember that the president probably his staff was not happy with him in doing this. But in an npr interview shortly after that talked about in the year 13 they would be at almost zero breakout time. So id like to understand what weve agreed to relative to their Nuclear Development capabilities after year ten. Ive asked the state department for the document. They havent given it to me. Ive asked the Energy Department for the document. They havent given it to me. Ive asked the white house for the document. They havent given it to me. The only thing i can imagine because they have not shared it with me and i know that it exists is that they think that it would shed bad light on what theyve agreed to. And i think it would cause people to have concerns after year ten what iran is able to do relative to the number of centrifuges, relative to the other kinds of development activities. And i think, wolf most of us want to make sure that if were going to enter into an agreement, its an agreement that will keep iran from developing a Nuclear Weapon over a long term. And i dont really understand unless theyre concerned about what this content is or how it might shed light on the deal thats happened i dont understand why they will not share with us what this document says. Again, its their view of what theyve agreed to relative to the Iranian Nuclear development program. So very quickly, mr. Chairman if they dont share that document with you and your colleagues even behind closed doors in a classified session, you wont be able to support any deal that emerges . Is that what im hearing . I cant imagine theyre not going to give it to us when they actually consummate this deal. But were having all kinds of briefings right now, wolf to make ourselves as uptodate as we can on where this is. Last night we met with three scientists the leaders of our National Laboratories around the country that are dealing with this issue, and the Energy Secretary to walk through the technical aspects. Theres so much of this that is classified that though its very technical we want to make sure that senators that are going to be dealing with this on the committee spend this e