MACDILL AIR FORCE BASE, Fla. (AP) _ One of the Army's most Iraq-savvy generals took charge Friday of arguably the most important command in the U.S. military, the one with responsibility for the wars in Iraq and Afghanistan.

In a ceremony attended by top Pentagon officials, Lt. Gen. Martin Dempsey assumed temporary command of U.S. Central Command, replacing Navy Adm. William J. Fallon, who relinquished his post after just one year in the assignment. President Bush has not yet nominated a permanent replacement.

Fallon had announced unexpectedly on March 11 that he was quitting, days after a magazine reported that he was at odds with President Bush over Iran policy. He said the report had become a distraction.

Dempsey, whose field experience in the early stages of his 34-year Army career was largely in Europe, has been deputy commander at Central Command since August 2007. He will serve as the acting commander until Bush chooses a permanent replacement and gets that person confirmed by the Senate.

Dempsey takes charge at a particularly sensitive time, not only because of heightened concern about relations with Iran and the uncertain outlook for the wars in Iraq and Afghanistan, but also because of the approaching November elections and the prospect of policy shifts by a new U.S. president.

"I am very proud to be part of this team," Dempsey said in brief remarks. "Now let's get back to work and see if we can make life a little better for our friends and a little more difficult for our enemies."

Fallon offered high praise for Dempsey, saying: "I can think of no one better qualified, more ready to do this than Marty. This command is going to be extremely well led. You've got more experience and more understanding of how things really are than anyone I've met in this area."

Defense Secretary Robert Gates noted the unusual circumstances facing Dempsey, who recently was confirmed by the Senate for promotion to four-star rank, but in a different job as commander of U.S. Army Europe. It is not clear whether Dempsey eventually will get that assignment or stay at Central Command. For now, Dempsey will remain at three-star rank, meaning he will be outranked by one of the commanders nominally in his charge: Army Gen. David Petraeus in Baghdad.

"Though this is an unexpected assignment for General Dempsey, I am confident that he is prepared to lead CentCom for as long as necessary," Gates said.

In remarks thanking Fallon for his service, Gates made no mention of Iran but praised Fallon as skilled and energetic, and said his work has shown tangible results in Iraq and Afghanistan. Fallon, who flew combat missions in Vietnam under the call sign "Fox," is retiring May 1 with the unusual distinction of having held four four-star positions, including chief of U.S. Pacific Command.

"When I recommended Admiral Fallon for this position, I told the president that the nation would benefit from one of the military's most experienced senior officers and one of its best strategic minds in one of the world's most complex regions," Gates said at the sun-splashed ceremony with an enormous American flag and a glistening Tampa Bay at his back.

"I had to work really hard to persuade Fox to take this job. (He) even worried a little bit that he was too old to start fresh at a new command. Since I'm older than he is, that didn't cut much ice. But Admiral Fallon tackled this role with unparalleled energy, insights, ideas and diplomatic skills."

Gates is 64; Fallon, 63.

Adm. Michael Mullen, the chairman of the Joint Chiefs of Staff, called Fallon "a war fighter's war fighter" and a "tough act to follow."

Fallon was the first Navy officer to head Central Command since it was created in 1983.

One of Fallon's final acts was to advise Bush and Gates on how to proceed in Iraq after July, when the last of the troop reinforcements that Bush ordered in 2007 are to have returned home. At points during his 13 months in charge at Central Command, Fallon was perceived as being at odds with Petraeus over how soon to end the troop surge.

Fallon made no reference to why he was leaving. He thanked and praised Bush and Gates and singled out Petraeus, calling him a "brilliant officer" with "amazing depth and ability to juggle a thousand balls. He's the principal instrument of success in our efforts in Iraq."

The retiring Centcom chief devoted much of his farewell speech, however, to recalling the ordinary soldiers, Marines, sailors and airmen he met on the front lines of combat in Iraq and Afghanistan, saying they are the real reason for the U.S. military's strength.

Bush is not expected to nominate a successor to Fallon until after Petraeus reports to Congress April 8-9 on his assessment of conditions in Iraq and his recommendations for how to proceed.

It is possible that Dempsey could get the job, but there are several other candidates, including Petraeus.

Dempsey knows Iraq well but has not served in Afghanistan. He earned high marks as commander of the 1st Armored Division in Iraq in 2003-04. For nearly two years prior to taking the Central Command job he served in Baghdad as head of the command that is training and equipping Iraqi security forces.

Dempsey graduated from the U.S. Military Academy at West Point and attended the National War College in 1995-96.

Copyright 2008 The Associated Press.