>> nbc news's allister jameson is in toulouse, france. people are trying to how officials can say this is definitely from mh-370 and other experts lingering after so many days. >> reporter: that's right. you have an extraordinary announcement by malaysia's prime minister and he used that word conclusively confirming that this was part of mh-370. and then a few hours later, giving this other announcement about other debris possible windows and aluminum foil found in the indian ocean. both announcements seemed to take other countries in this very complex international investigation somewhat by surprise. and certainly they are not ready, french authorities here are not ready to make that same call. they have a lot of experience in carrying out these investigations. they agree that it's very likely that the boeing 777 wing component being tested in this lab behind me is part of mh-370.