The Obama administration has intensified the American covert war in Yemen, exploiting a growing power vacuum in the country to strike at militant suspects with armed drones and fighter jets, according to American officials.
The acceleration of the American campaign in recent weeks comes amid a violent conflict in Yemen that has left the government in Sanaa, a United States ally, struggling to cling to power.
Yemeni troops that had been battling militants linked to al Qaeda in the south have been pulled back to the capital, and American officials see the strikes as one of the few options to keep the militants from consolidating power.
The recent operations come after a nearly year-long pause in American airstrikes, which were halted amid concerns that poor intelligence had led to bungled missions and civilian deaths that were undercutting the goals of the secret campaign.
The American campaign in Yemen is led by the Pentagon's Joint Special Operations Command, and is closely coordinated with the Central Intelligence Agency.
Teams of American military and intelligence operatives have a command post in Sanaa, the Yemeni capital, to track intelligence about militants in Yemen and plot future strikes.
Concerned that support for the campaign could wane if the government of Yemen's authoritarian president, Ali Abdullah Saleh, were to fall, the US ambassador in Yemen has met recently with leaders of the opposition, partly to make the case for continuing American operations.
Officials in Washington said opposition leaders have told the ambassador, Gerald M Feierstein, that operations against al Qaeda in the Arabian Peninsula should continue regardless of who wins the power struggle in Sana.
The extent of America's war in Yemen has been among the Obama administration's most closely guarded secrets, as officials worried that news of unilateral American operations could undermine Saleh's tenuous grip on power.
Saleh authorised American missions in Yemen in 2009, but placed limits on their scope and has said publicly that all military operations had been conducted by his own troops.