peter neumann studies and teaches terrorism and radicalization at king's college in london. oins me now from there to discuss the group and its intentions. peter, these latest attacks put to rest the idea that isis was mostly concerned about actions in the middle east. what do you think that they are trying to accomplish with these most recent attack sms. >> i think there are three aims here. the first is classical asymmetric warfare, you're hitting us, we're going to take revenge by hitting you where it hurts most, namely, at home. the second intention is really to polarize and divide european societies, to create that sense of islam against the west and to create a lot of mess in the countries that they oppose. the third intention that often gets forgotten is often internally. i think the islamic state has been on the defensive in its core territory in iraq and syria and this kind of attack, i think, motivates supporters and gives them, again, the feeling that they are part of a winning team and that's really important. >> brangham: so this is part of their strategy of not

there's a nice report by peter neumann in the new england journal this week about the different approachesnd so the challenges in them. on the one hand, it's very hard to capture all of these dimensions in a way that makes sense for patients that have different preferences about how they want to trade off safety issues and cost issues and health outcome issues. on the other hand, there is a lot of evidence that the value of the drugs on the market today very tremendously with some drugs, some specialty drugs and some indications worth on the order of $2000 per quality adjusted life year, a very good value. others at $200,000, $500,000 or more. again different methods lead to different interest. these are challenging estimates to calculate that no question a lot of variation out there in the context of what have been some really valuable contributions to improving health. and with that framing, no wonder there's so much attention to the cost of prescription drugs and rising costs. we are seeing a shift in prescription drugs in spending towards more first in class of drugs. you heard earlier