Bomb Plot: UK and US Disagreed on Decision to Intervene?

US and UK investigators differed on the decision to intervene in the British bomb plot, NBC says:

British officials knowledgeable about the case said British police were planning to continue to run surveillance for at least another week to try to obtain more evidence, while American officials pressured them to arrest the suspects sooner.

The sources did say, however, that police believe one U.K.-based suspect was ready to conduct a "dry run." British authorities had wanted to let him go forward with part of the plan, but the Americans balked.

Aside from the timing issue, there was excellent cooperation between the British and the Americans, officials told NBC News.

This seems like a reasonably healthy difference of opinion, based on a judgment as to the imminence of the attack. The decision to intervene is never easy, and a lot of factors have to be weighed.

Update: The New York Times also reported on the issue.