CAMP RAMADI, Iraq (AP) - The top U.S. Marine is checking on troops in one war zone as he gets ready to send more to the next.

Gen. James Conway, commandant of the Marine Corps, visited Iraq this week before flying Saturday to Afghanistan, where the United States is considering adding more troops. Many of the fresh-faced Marines who met Conway are serving their first combat mission - and already are looking forward to the next battle.

They are part of a force that, between the years in Iraq and Afghanistan, could be fighting wars for a generation.

At a hot and dusty base outside Ramadi, the capital of Iraq's Anbar province, Conway made clear he does not yet know whether Army Gen. Stanley McChrystal, the U.S. and NATO commander in Afghanistan, will add to the 68,000 American troops already scheduled to be there by the end of the year. But Conway told the Marines he wants them to be ready.

"I'll be surprised if we don't get asked for more," Conway said. He predicted "more combat support in there."

McChrystal is preparing a review of his war - and his needs for fighting it. He is expected to deliver that review to the Pentagon by early September. Defense Secretary Robert Gates last week said the review will not address troop levels, but military officials privately believe McChrystal ultimately will ask for as many as 20,000 additional soldiers.

U.S. troops first invaded Afghanistan in 2001 after the Sept. 11 terrorist attacks, and Iraq two years later. Although the United States is committed to pulling its combat forces from Iraq by the end of 2011, military officials and experts believe the battle in Afghanistan easily could last for up to a decade longer.

That has required the Pentagon to rethink how to prepare its forces. The Army is recruiting 22,000 new soldiers and extending time at home for troops returning from battle. The Marines are making physical fitness more rigorous for those headed into combat.

Marines being Marines - a force that prides itself on running from one fight to the next - appear eager to head from Iraq to Afghanistan. An estimated 13,200 Marines remain in Iraq, and the vast majority of them will be gone by Thanksgiving. About 11,400 Marines are currently in Afghanistan.

"We're an expeditionary force; we're very offensive-minded, and it would be a better use of our time to be in Afghanistan," said Capt. John Roma, commander of a Marine company that deployed to Iraq just two weeks ago. It's his second tour of duty in Iraq; he has also fought in Afghanistan.

"But we still have a job to do here, and we're doing it to the best of our ability."

All troops will receive at least as much time at home between deployments as they spent in combat, meaning those currently in Iraq will not go to Afghanistan immediately.

Whether the U.S. should send more troops to Afghanistan is part of a simmering debate in Washington over how much money, and ultimately, time should be spent on the war. A recent policy paper by the Center for Strategic and International Studies, a Washington think tank, warned against shortchanging the war in Afghanistan.

"Adequate resources win in Iraq, inadequate resources lose in Afghanistan: Late in one case, still waiting in the other," the CSIS paper concluded.

Under a security agreement with the Iraqi government, U.S. troops no longer operate in Iraqi cities without permission or escort by local Iraqi forces. In Anbar, that means Marines have scaled back their missions to the point of being bored, even though violence between Iraqis continues.

A pair of deadly bombs this week in Baghdad killed nearly 100 people and wounded hundreds more. In July 2007, 203 coalition forces were killed by improvised explosive devices, military figures show. By comparison, IED blasts killed nine troops last month.

But security remains fragile, and some local Iraqi officials are evasive about whether they want Americans to help protect them from insurgents and other threats even as the troops prepare to move on.

Saeed Hamadan, mayor-elect of Hit, in Anbar, said Baghdad gets the most attention but his city faces the same threats as the rest of Iraq.

"We see explosions every day," Hamadan said in his office last week.

In an interview with The Associated Press, Conway said that in Afghanistan up to 700 troops should be added or, at the least, retasked to focus on IED attacks. He estimates such attacks have caused 80 percent of Marine deaths since May, when the U.S. launched a major offensive against the Taliban in southern Afghanistan.

He would not discuss how many troops ultimately could be added to the fight, except to say that he does not want it to go beyond 18,000 more Marines, or he won't be able to protect the length of Marines' time at home between war zones.

"The most important thing that's happening is right here in Iraq," Conway said during a question-and-answer session with troops at Camp Taqqadum air base, 35 miles west of Baghdad. "The most difficult thing that's happening for our Corps today is in Afghanistan. And I think we're going to be there for a while, and if you all want to go to Afghanistan - that's been my experience from talking to most Marines - then you may well get that chance."