From one war front to another Sunday, Pentagon chief Leon Panetta hopped from a U.S. outpost in Afghanistan's southern desert to Baghdad, where he sought to encourage Iraqi leaders to decide soon whether they want a residual American military force beyond year's end.

He refused to say whether the Obama administration wants the extension, but he expressed concern at a spike in U.S. deaths caused by what American officials believe are sophisticated explosive devices made in Iran.

Panetta prepared for talks Monday with Prime Minister Nouri al-Maliki and other senior members of a government politically divided more than a year after national elections. Iraq has gone that long without defense or interior ministers, whose departments are responsible for the military and police.

The approximately 46,000 U.S. troops remaining in Iraq are to depart by the end of 2011 under an agreement negotiated in 2008 by the Bush administration, which went to war in 2003 to topple Saddam Hussein's government.

Asking even a few thousand to stay longer carries political risk leaders in both countries.

A signature pledge of President Barack Obama 2008 election campaign was to get the U.S. out of Iraq. For Iraqis fed up with violence, a longer U.S. presence looks like a formula for further strife.

The Associated Press reported on July 5 that the White House is offering to keep up to 10,000 troops in Iraq next year, despite opposition from key Democrats who demand that Obama bring home the troops as promised.

Panetta spent Sunday afternoon at Camp Dwyer, a dust-choked U.S. outpost in southern Afghanistan. He pinned Purple Heart medals on two Marines, had lunch with young officers, got a glimpse at an Army Black Hawk medevac unit and quizzed an Afghan army officer on commanding a unit that specializes in detecting land mines and roadside bombs.

The 73-year-old Panetta, on the job since July 1 after 2 1/2 years heading the CIA, appeared to hold up well under the intense heat. But at one point he seemed to lose track of his latest job switch. In a pep talk to a group of Marines, he said he has always valued public service, from his time in the Army in the 1960s to eight terms as a congressman and his years in the Clinton White House, "and now as director of the CIA."

At issue in Baghdad is whether the Iraqi government will request that the U.S. negotiate a troop extension. The scheduled departure of virtually all U.S. troops by Dec. 31 will leave the country with significant gaps in its ability to defend its own airspace and borders.

Panetta's predecessor at the Pentagon, Robert Gates, visited Iraq in April to push for an early decision and make clear that Washington believes an extension is in both countries' interest.

Panetta, however, seemed less willing to commit to a residual force.

Speaking to reporters before boarding his plane for the flight to Iraq from Camp Dwyer in southern Afghanistan, Panetta was asked whether he intended to encourage the Iraqis to request an extension.

"I'll encourage them to make a decision" about what they want, he replied, leaving open the question of what the White House would accept.

Panetta said he thinks U.S. should consider any Iraqi request and he said Obama "feels we ought to consider it as well." Obama has said repeatedly over the past year that he is responsibly ending the Iraq war and bringing U.S. troops home this year.

Panetta said he also intended to urge Iraqi leaders to do more to go after Shiite militia groups that are using Iranian-supplied weapons to step up attacks on U.S. troops. The U.S. death toll of 15 in June was the highest for any month in the past two years, Panetta said.

"That has concerned us," he said, adding that Iraqi Shiite militiamen using Iranian weapons need to be targeted more aggressively. Pentagon officials believe the Iranians are providing more arms, such as airborne makeshift "lob bombs" and explosively formed projectiles, to give the impression of driving U.S. troops out of Iraq. Panetta came to his new job with links to the wars in Iraq and Afghanistan, even if he was not directly involved in military strategy.

He visited both countries during his CIA tenure. Both wars have an unusually heavy intelligence component, with U.S. special operations teams taking on al-Qaida and other insurgents.

One concern about the plan to withdraw all U.S. forces from Iraq by the end of this year is that Iraq's intelligence services are not yet up to the task of adequately supporting counterterrorism forces.

Panetta was a member of the Iraq Study Group, created by Congress in 2006 to consider a better way forward in a war that was spiraling out of control at the time. Coincidentally, Panetta served on the group with Gates until Gates quit because he was picked to replace Donald H. Rumsfeld as defense secretary.

Panetta signed off on the group's final report, which concluded that it was time to get all U.S. ground combat brigades out of Iraq, leaving troops to train the Iraqi army and to undertake strikes against al-Qaida cells.

President George W. Bush took a decidedly different course, ordering troop reinforcements to Iraq as part of a new strategy that is widely credited for turning around the war.

The U.S. military reported that a service member was killed Sunday in southern Iraq and that the matter was under investigation.