WASHINGTON - After the nation's top U.S. intelligence official fumbled a simple question about terrorism on national television, the White House on Wednesday acknowledged that James Clapper, the director of national intelligence, had been in the dark about a terrorist plot disrupted in England.

It was an inconvenient distraction for the Obama administration, which had hoped to use the day to reassure Americans that it had fixed the mistakes that nearly allowed al-Qaeda to take down a U.S.-bound airliner last Christmas.

Clapper appeared stumped Tuesday night when asked on ABC News whether a significant terror plot uncovered in London could have security implications in the United States. The plot had received huge news coverage this week and was a major focus in the United Kingdom, America's closest intelligence partner.

"London?" Clapper asked, looking across the table at Obama's homeland security adviser, John Brennan, who was also being interviewed.

In practice, British and U.S. authorities work hand-in-hand on such cases regardless of how involved senior intelligence officials get. But it was an embarrassing moment for the embattled position of director of national intelligence. The job, created after the 9/11 terrorist attacks, has failed to live up to its billing as a central, strong overseer of the nation's intelligence infrastructure.

And the image of Clapper turning, perplexed, to Brennan only reinforced the impression by many in the intelligence community that it is Brennan who really controls the nation's intelligence apparatus. Before his confirmation, one of the criticisms of Clapper was that he would not have the clout to take charge of the nation's far-flung intelligence network. With Brennan, a former CIA official, in the White House, and CIA Director Leon Panetta running the nation's spy agency, some lawmakers feared that Clapper would be marginalized.

At a White House news briefing, Brennan said Clapper had been preoccupied with tensions between North and South Korea and helping ensure the passage of a nuclear-weapons treaty with Russia.

"Should he have been briefed by his staff on those arrests?" Brennan said. "Yes."

In a city where television appearances are heavily scripted affairs and government leaders rarely get caught off guard, Clapper's misstep was as much a failure of media preparation as it was of actual intelligence. Nevertheless, it forced the White House off its message of reassurance to the American public.