Transcript for Security implications of deadly Manchester blast

More from our chief global affairs anchor Martha Raddatz, counterterrorism expert Matt Olsen. One of the most chilling things, the apparent targeting of young girls and their families. Reporter: You know, we don't know whether it was to target the concert of an American performer but you know we say the word terrorism so often, you can forget the meaning. It is to make you terrified, vulnerable. To affect your daily living and second-guess what you do, where you go and have heard people in Manchester and the uk say it will not affect how they live but truly there is nothing more terrifying than thinking your children might be harmed, especially if you were not there with them, so this bomber took terrorism to a new low level to strike directly at the heart of the uk, George. And, Matt, from what we know about this right now from what we know about the target and know about this backpack bomb what does it tell you about the background of the attack. Everything you see so far does point to some type of islamist terrorist attack. This is the hallmark of groups like ISIS and Al Qaeda. Suicide bombers, soft targets, as was reported this is not unlike what we saw in Paris at the Bataclan theater and again this takes place against the backdrop of calls by ISIS and Al Qaeda for carrying out attacks like this in places like the uk as well as here in the united States. What you don't have yet is a claim of responsibility, Matt. What does that tell you? Often there's no claim of responsibility for some period of time. What we might have here as we've seen in the past is an individual or perhaps group of individuals who were inspired by the message of ISIS or Al Qaeda as opposed to directed by those groups and in what you see is that some period of time after the attack those groups then claim those individuals as their soldiers or their followers and that may well be what we have in this case. The people in Manchester determined to go back to daily life but also likely to inflame anti-islamic sentiment across Europe and Britain. Manchester itself is a very mul multicultural city with a large Muslim population sore head scarves attack little attention and Manchester did not vote in favor of brexit, but an attack like this as you said is much bigger than Manchester itself and will likely create backlash depending on the details of this attack. We saw that statement from mi5 and know U.S. Intelligence agencies have quite a close relationship with British officials. Yeah, that said the relationship is as close as any we have with any other country. You can be sure that overnight U.S. Officials, analysts were in their offices working with their counterparts in the uk starting with thedentity of this individual which the authorities do know and then working out to see did he act alone? How was he radicalized? Who supported him? Where did he get the money and training to build a bomb like this so the investigation is just under way but working closely between the united States and uk for sure. Matt Olsen and Martha Raddatz, thanks. We'll continue to bring

This transcript has been automatically generated and may not be 100% accurate.