U.S. Gen. David Petraeus formally took command of international forces in Afghanistan Sunday, telling NATO and Afghan officials "we are in this to win" despite a rising death toll among coalition troops.

Petraeus received two flags during a ceremony at NATO headquarters in Kabul, an American flag and a NATO flag, to signal his takeover of command.

Petraeus said it was imperative for the 130,000-strong international force to prevent al Qaeda and other extremist elements from taking over in the country.

"We are in this to win," Petraeus said. "We have arrived at a critical moment."

Petraeus took command after Gen. Stanley McChrystal was relieved of his duties following the publication of an interview in which he and his aides criticized members of the Obama administration.

In his speech, Petraeus acknowledged the "enormous contributions of my predecessor" and said the change of command would not also mean a change of strategy in the war-torn country.

However, he did say he would review both civilian and military policies to determine what changes, if any, should be made.

Some soldiers have been critical of McChrystal's decisions to curb air strikes and instruct soldiers to avoid firing their weapons if civilian lives were at risk.

"We must never forget that the decisive terrain in Afghanistan is the human terrain," Petraeus wrote Sunday in a memo to his troops. "Protecting those we are here to help nonetheless does require killing, capturing or turning the insurgents. We will not shrink from that."

CTV's South Asia Bureau Chief Janis Mackey Frayer said Sunday soldiers will get a similar commander in Petraeus to the one they had in McChrystal.

"In terms of the doctrine, it's pretty much the same," Mackey Frayer told CTV News Channel in a telephone interview from Kabul. "They're both architects of the counter-insurgency strategy that's being employed here. It's one that rests on the fact that the war will be won by winning the people."