KABUL, AFGHANISTAN - As Sen. Barack Obama heads to Iraq today for his first visit as a presidential candidate, his plan for bringing the war to a swift conclusion is triggering a political furor abroad and at home, with a U.S. military leader declaring Sunday that setting a hard deadline for withdrawing troops is risky.

In Iraq, Obama is scheduled to meet with political leaders who were scrambling over the weekend to clarify an apparent endorsement of his proposal to pull U.S. forces out of Iraq in 16 months.

On Sunday he met with Afghan President Hamid Karzai, describing the ongoing conflict in Afghanistan as the central front in the U.S. fight against terrorism, according to Karzai aides. The presumptive Democratic nominee wants to wind down U.S. involvement in Iraq and redeploy troops and resources to Afghanistan, a country he said has devolved yet again into a sanctuary for terrorists intent on harming the United States.

"There is starting to be a growing consensus that it's time for us to withdraw some of our combat troops out of Iraq, deploy them here in Afghanistan," Obama said during an interview on CBS' "Face the Nation." "And I think we have to seize that opportunity. Now is the time for us to do it."

But Adm. Michael G. Mullen, chairman of the U.S. Joint Chiefs of Staff, stepped into the debate Sunday, saying in an appearance on "Fox News Sunday" that setting a two-year deadline to pull all troops out of Iraq would not be advisable.

"I think the consequences could be very dangerous in that regard," Mullen said. "I'm convinced at this point in time that making reductions based on conditions on the ground are very important."

Randy Scheunemann, a foreign policy adviser for Obama rival Sen. John McCain, said in a prepared statement: "Barack Obama says he wants a 'safe and responsible' withdrawal from Iraq, but is stubbornly adhering to an unconditional withdrawal that places politics above the advice of our military commanders, the success of our troops and the security of the American people."

Obama's plan to close out the war had seemed to win the validation of the Iraqi prime minister, Nouri al-Maliki. In an interview with a German magazine published Saturday, al-Maliki said the 16-month deadline "would be the right time frame for a withdrawal."

But on Sunday, an al-Maliki spokesman said the magazine, Der Spiegel, had misinterpreted the prime minister's comments.

The spokesman, Ali al-Dabbagh, said al-Maliki had told the magazine that improved security in Iraq would permit the exit of U.S. forces within certain "horizons and timelines" -- language that more closely tracks the Bush administration's official position.