America's top military officer, Admiral Michael Mullen, says the transition to a new U.S. administration could be a time of heightened threat for the United States.  The Chairman of the Joint Chiefs of Staff, who spoke in Los Angeles Monday, said the next president must address a growing insurgency along the Afghanistan-Pakistan border.  From Los Angeles, Mike O'Sullivan files.

The 44th U.S. president will take the oath of office on January 20.  And Admiral Mullen says the months around the inauguration are always a time of transition and risk as a new administration gets up and running.

He says the most serious threat comes from the border region between Afghanistan and Pakistan, where, he says, the level of violence has been rising. 

Earlier this month, Mullen told a congressional committee that he is not convinced that coalition forces are winning in Afghanistan.  But, he says, he believes they can.  He repeated the comment on Monday before an audience in Los Angeles, and later told reporters, that the United States needs to focus on the Afghanistan-Pakistan border.

"Al-Qaida is there.  Its leadership is there.  We know that.  And it continues to plan against the West, including against our homeland," he said.

Pakistan has criticized a series of suspected U.S. missile strikes and a ground attack against militant targets in Pakistan.

Pentagon officials deny news reports that Pakistani soldiers fired at two U.S. helicopters late Sunday for allegedly violating Pakistan's airspace in a suspected attack on a militant base.  Admiral Mullen said he has received no information that such an incident happened.

Speaking in Washington Monday, Afghanistan's defense minister said his country has proposed a joint force made up of Afghan, Pakistani and coalition troops that would operate on both sides of the border.  Admiral Mullen said he has not seen details of the proposal, but is encouraged that an Afghan leader offered the idea as a way to increase border security.

Mullen says the coalition strategy in the region needs to be economic as well as military.  He says it should focus in part on eradicating poppy production, which fuels the heroin trade and feeds a growing insurgency.

"The profits from that crop are feeding the fight.  And the extension of that is, they're killing Americans and killing our coalition partners and killing Afghan soldiers and citizens," added Mullen.

In addition, Admiral Mullen says Iran must also be a top priority for the new administration.  He says Tehran hopes to extend its influence beyond the Middle East, and that it is working with the Taliban, once its archenemy, against coalition forces in Afghanistan.