threats coming from within our borders. emily schmidt has the details this morning from washington. good morning, emily. reporter: rob and vinita, good morning to you. the u.s. counterterrorism chief says over the past year, we ve seen more significant terror developments than any year since 9/11. there are more threats. and they re happening closer to hope home. top intelligence officials say fighting terrorism is getting more complicated because extremists are looking for help from people within u.s. boarders. a new and changing facet of the terrorist threat comes from homegrown terrorists. by which, i mean, u.s. persons. reporter: there were three attempted attacks in seven months. first, last year s new york subway plot. then, the christmas day square. and the times square bombing attempt in may. in the last year and a half, 63 americans have been arrested or convicted of terroristic charges. do you believe this is an aberration? or is this likely to continue?
since 9/11, all of us in america have lived with the prospect of another terrorist attack. and today, top counterterrorism officials appear before congress with a warning. they said the danger is as grave as it has been since september 11th, nine years ago, and they said al qaeda has new ways of recruiting people inside this country. pierre thomas followed all the testimony today and joins us now. pierre? reporter: diane, we watched what these intelligence officials had to say very closely. and i can tell you, their tone today was especially stark. the past year has noted the most significant developments in terrorism since 9/11. reporter: in the last 18 months or so, at least 63 americans have been arrested or convicted of terrorism charges. that s an astoundingly high number. we have seen a dramatic spike. do you believe this is an aberration or is this likely to continue? caution would dictate that we assume it is not an aberration. reporter: the warning was