© Alex Wong / Getty ImagesWith Stanley McChrystal's resignation, General Petraeus moves from overseeing all U.S. forces in the Middle East to running operations in Afghanistan
President Obama removed Gen. Stanley A. McChrystal as commander of U.S. and NATO forces in Afghanistan on Wednesday, moving quickly to restore the unity of his administration's war effort after the general and his top aides disparaged civilian leaders in biting remarks in an explosive magazine article.

Obama named Gen. David H. Petraeus, the former commander of U.S. forces in Iraq and currently the head of the U.S. Central Command, to replace McChrystal and urged the Senate to confirm him promptly.

But Obama reaffirmed in blunt terms the counterinsurgency strategy he ordered last year, and he said that "war is bigger than any one man or woman, whether a private, a general or a president."

A senior military official said it has not yet been determined whether Petraeus's move to take charge in Afghanistan will be permanent.

Speaking in the White House Rose Garden after a 30-minute meeting with his national security team in the Situation Room, Obama indicated that he had effectively lost confidence in McChrystal's ability to implement the surge in forces that Obama approved at McChrystal's request late last year.

"Today I accepted General Stanley McChrystal's resignation as commander of the International Security Assistance Force in Afghanistan," Obama said in an appearance in the White House Rose Garden. "I did so with considerable regret but also with certainty that it is the right thing for our mission in Afghanistan, for our military and for our country."

Obama said he did not make his decision based on any policy differences with McChrystal or "out of any sense of personal insult." But he made clear that the remarks attributed to the general and his aides could not be tolerated.

"The conduct represented in the recently published article does not meet the standard that should be set by a commanding general," Obama said. "It undermines the civilian control of the military that is at the core of our democratic system. And it erodes the trust that's necessary for our team to work together to achieve our objectives in Afghanistan."

Obama said it was his "duty to ensure that no diversion complicates the vital mission" of U.S. forces in Afghanistan," and he stressed that American democracy depends on "strict adherence to the military chain of command, and respect for civilian control over that chain of command."

Saying that success in Afghanistan and in the broader fight against the al-Qaeda terrorist network demands a unified effort, Obama said he concluded that the United States and its allies could not "sustain that unity of effort . . . without making this change."

He said he told his national security team that "now is the time for all of us to come together." He added: "Doing so is not an option, but an obligation. I welcome debate among my team, but I won't tolerate division."

It was the second time that Obama has fired his top Afghanistan commander as he searches for a way to bring the nearly nine-year-old war to a successful conclusion. He had turned to McChrystal as a replacement for Gen. David McKiernan last year.

The president informed McChrystal of his decision in a brief, 30-minute face-to-face meeting in the Oval Office. McChrystal quickly left the White House after the meeting, leading to speculation that he would not be returning for the national security team conference, which he previously had been scheduled to attend.

But no announcement was made for several hours, as Obama conferred with the other military and civilian leaders who will continue to lead the war effort.

In a statement issued by his headquarters in Kabul, McChrystal said Obama "accepted my resignation as commander of U.S. and NATO coalition forces in Afghanistan." He added: "I strongly support the president's strategy in Afghanistan and am deeply committed to our coalition forces, our partner nations, and the Afghan people. It was out of respect for this commitment -- and a desire to see the mission succeed -- that I tendered my resignation."

In relieving McChrystal of duty, Obama went out of his way to praise his long service in the military. Obama said McChrystal has "earned a reputation as one of our nation's finest soldiers."

But he also said he is convinced that his decision is the right one for the country. And he said it should not be read by anyone as a change in the direction of the country's war effort.

"This is a change in personnel," Obama said, "but it is not a change in policy."

Obama's decision was telegraphed on Tuesday, when White House press secretary Robert Gibbs refused repeated opportunities to offer any assurances that McChrystal's job was secure. Gibbs called the remarks and behavior of the general and his aides an "enormous mistake" and said Obama was "angry" about comments reported by Rolling Stone.

Petraeus, 57, took over in October 2008 as head of the Central Command, overseeing all U.S. forces in the Middle East. He previously commanded U.S. forces in Iraq and was credited with implementing a strategy that turned the tide against insurgents and sectarian groups in that war.

McChrystal, 55, who was named by Obama last year to run the war in Afghanistan, saw the president after conferring Wednesday morning at the Pentagon with Defense Secretary Robert M. Gates and Adm. Mike Mullen, chairman of the Joint Chiefs of Staff.

The meeting with Obama began at 9:51 a.m. in the Oval Office and lasted about half an hour. It preceded a scheduled conference of Obama's national security team on Afghanistan and Pakistan in the White House Situation Room. Among the top officials originally slated to attend, according to the White House, were McChrystal and several of the people he and his aides had disparaged.In addition to Obama, those attendees included Vice President Biden, National Security Adviser James L. Jones and, by video conference, special envoy Richard C. Holbrooke and U.S. Ambassador to Afghanistan Karl W. Eikenberry.

Obama later postponed a previously scheduled lunch with senators and decided to skip a 2:50 p.m. event on physical fitness and nutrition, sending first lady Michelle Obama instead.

In response to the disparaging comments, an angry Obama had left open the option of firing McChrystal, Gibbs said Tuesday.

But in Kabul, Afghan President Hamid Karzai cautioned Obama against replacing the commander of the U.S. and NATO war effort.

In a video conference call with Obama on Tuesday night, Karzai said "that we are in a very sensitive juncture in our partnership and our war on terror," Karzai spokesman Waheed Omer said in a news conference Wednesday. "Any gaps in this process would not be helpful."

During the call, Obama told Karzai that he would not rush to a decision on whether to fire McChrystal, Omer said.

Later, after Obama announced the removal of McChrystal, Afghan officials said they were saddened and disappointed to see him go, but they took heart from the nomination of Petraeus to replace him. Omer said Afghan leaders view Petraeus as "another trusted partner."

In Washington, the move promptly won bipartisan support on Capitol Hill of McChrystal, titled "The Runaway General," started circulating.

Aides quoted anonymously in the article accused Obama of being uninformed and disengaged during his first solo meeting with the general, in spring 2009. And they described Karzai as being "locked up in his palace this past year" and out of the loop, even as the U.S. strategy in Afghanistan relied on making the Afghan government a strong and credible partner.

The controversy over the article comes amid a U.S. troop surge requested by McChrystal and a spike in NATO casualties that has raised alarm in Washington and NATO capitals.

On Wednesday, NATO announced that two American troops died the day before in bombings in southern Afghanistan, where the radical Islamist Taliban movement has stepped up attacks as the U.S.-led international force has attempted to wrest control of their strongholds.

So far this month, at least 59 NATO troops, including 43 U.S. service members, have been killed in Afghanistan. That means June is on pace to become the deadliest month for NATO troops in the nearly nine-year war.

Londoño reported from Kabul. Karin Brulliard in Islamabad and Javed Hamdard in Kabul contributed to this report.