Kabul - Ten days after his predecessor was fired over remarks that laid bare a dysfunctional civilian-military relationship, the new American commander in Afghanistan sought Saturday to put a unified face on the U.S.-led war effort.

U.S. Army Gen. David H. Petraeus, who arrived Friday to assume command of U.S. and Western forces here, made his public debut in Kabul at a Fourth of July weekend celebration at the U.S. Embassy.

He and U.S. Ambassador Karl Eikenberry, who presides over the world's largest American diplomatic mission, used brief remarks there to drive home the message that they would heed President Barack Obama's stern order to put aside internal rivalries.

"We look forward to being your teammates," Eikenberry told Petraeus, whom he referred to at one point as "Dave."

The ambassador ceremonially presented the camouflage-clad general with an access badge to the sprawling diplomatic compound and said: "You're welcome at this embassy 24-7."

"I feel like one of the team," Petraeus told about 1,700 invited guests, who included military and diplomatic personnel, together with a number of Afghan dignitaries.

"Cooperation is not optional," he added. "This is a tough mission."

Petraeus replaces fellow four-star Gen. Stanley A. McChrystal, who had led the war effort for the last year. McChrystal's military career was abruptly ended by remarks made by him and top aides in an explosive profile that appeared in Rolling Stone magazine.

In it, McChrystal and his team disparaged Vice President Joe Biden and expressed irritation with special regional envoy Richard C. Holbrooke. One of McChrystal's senior aides was quoted as calling Obama's national security adviser, James L. Jones, a "clown."

McChrystal was quoted as saying the American ambassador "covers his flank for the history books" - a reference to leaked diplomatic cables last year in which Eikenberry expressed reservations about the scope of the troop surge urged by McChrystal. He also branded Afghan President Hamid Karzai an unreliable partner.

Recent days have brought a concerted effort to set a new tone. Petraeus stopped in Brussels en route to Kabul to brief NATO allies about the state of the war, and Eikenberry accompanied him back to the Afghan capital.

Many observers believe it is difficult to know how the relationship of Petraeus and Eikenberry will play out. The military-civilian partnership is a key element of the American strategy in Afghanistan, which calls for battlefield pressure on the Taliban to be tightly linked to improved governance meant to win over the population.

Petraeus was a friend and mentor to McChrystal, and a driving force behind the counterinsurgency strategy that McChrystal had been working to implement. Some of those close to the ousted general blame the American envoy, at least in part, for fostering the antagonistic climate that led to the McChrystal's intemperate remarks.

Karzai, whose relationship with the Obama administration has been strained by widespread allegations of corruption in his government, was not present for Saturday's festivities, although the presidential palace said he was in the capital. He sent his foreign minister, Zalmay Rasul, to represent him.

Petraeus was to formally assume command at a ceremony today at the Kabul headquarters of NATO's International Security Assistance Force, where McChrystal took part in a similar ritual a year ago.