WASHINGTON - The United States is looking at ways to expand military and intelligence cooperation with the government of Yemen to step up a crackdown on al Qaeda militants believed to be behind a failed plot to blow up a U.S. passenger jet, American officials said on Wednesday.

President Barack Obama has vowed to bring every element of U.S. power against those who threaten Americans' safety, but offered no specifics.

Pentagon spokesman Bryan Whitman declined to comment on any military planning, but called a television report that the United States was preparing for possible retaliatory strikes grossly exaggerated.

We are going to work with allies and partners to seek out terrorist activity, al Qaeda... This is not new, Whitman said.

Other defence and counterterrorism officials suggested Yemen, with U.S. assistance, would likely take the lead in any expanded crackdown, playing down prospects for a sharp military escalation led by the United States.

Obama faces a difficult balancing act.

A more direct and forceful U.S. role in responding to the Christmas Day plot, which was claimed by Al Qaeda in the Arabian Peninsula, might be popular within the United States, but risks undermining the standing of the government of Yemen and increasing public support there for the militants.

Defence and counterterrorism officials, speaking on condition of anonymity, said the Obama administration was exploring ways to accelerate and expand U.S. assistance to Yemeni forces to root out the al Qaeda leadership in the country, while keeping the role of the U.S. military and intelligence agencies as behind the scenes as possible.

Where the United States can be of assistance, we're going to offer our assistance, said a defence official, who spoke on condition of anonymity. We're working to build partnership capabilities to enable them to take on the al Qaeda threat inside their country.

We have a country in Yemen willing to accept U.S. assistance, the official added.

The United States has sharply increased the amount of military equipment, intelligence and training it provides to Yemeni forces, helping them carry out air raids against suspected al Qaeda hide-outs earlier this month.

U.S. defence and counterterrorism officials said more military operations led by Yemeni forces were likely in response to the attempted bombing of the Delta Airlines jet as it was approaching Detroit on a flight from Amsterdam with almost 300 people on board.

Much of the U.S. military aid has been covert, in part to avert a public backlash against the Yemeni government, which, on top of al Qaeda, is battling Shi'ite rebels in the north and faces separatist sentiment in the south.

The Pentagon's main publicly disclosed counterterrorism assistance program for Yemen has grown from just $4.6 million (2.8 million pounds) in fiscal 2006 to $67 million in fiscal 2009, Pentagon spokesman Bryan Whitman said.

Whitman said Yemen was the second-largest recipient of counterterrorism aid under the overt program, behind Pakistan.

Pentagon officials said the military has proposed increasing the amount of counterterrorism support for Yemen.

Whitman said a figure has yet to be finalized but that an increase appeared to be probable.
When you talk about where there are terrorist challenges, where there is the potential for partnership-building, Yemen is certainly up there along with Pakistan, he said.