Washington ? Saying they obtained new evidence, senior White House officials said Sunday that the Pakistani Taliban were behind the failed Times Square bombing.

The attempt marks the first time the group has been able to launch an attack on U.S. soil. And while U.S. officials have downplayed the threat — citing the bomb’s lack of sophistication — the incident in Times Square and Christmas Day airline bomber indicate growing strength by overseas terrorist groups linked to al-Qaida even as the CIA says their operations are seriously degraded.

The finding also raises new questions about the U.S. relationship with Pakistan, which is widely known to have al-Qaida and other terrorist groups operating within its borders.