Former president Bill Clinton said the U.S. strategy in Iraq threatens to draw resources from the "even more important" priority of securing Afghanistan.

Clinton, interviewed yesterday on ABC's "This Week," said the United States will not know if Iraqis can muster enough trained security forces to fight the insurgency until the process of approving a constitution by national referendum and forming a permanent government is completed by the end of the year.

The question is whether the U.S. force of about 140,000 troops is enough to meet the strategic goal of securing Iraq while helping the country develop its police and army forces, he said.

"I wanted the strategy to work," Clinton said. "Whether it will or not, I don't know. But the only thing I would sacrifice it to is if I thought we were going to lose in Afghanistan."

Clinton said keeping Afghanistan out of the hands of the Taliban and undermining al Qaeda should be the biggest priorities for the United States, because "that's still by far a bigger threat to our security."

He said he agrees with President Bush's refusal to set a timetable for the withdrawal of U.S. forces in Iraq because there is "no reasonable prospect" that the insurgents otherwise can be brought into the political process.