"We cannot get those [Afghan] soldiers to sufficient numbers until 2012, 2015 at the latest," Keane said. "That's why McChrystal has come forward and says I have to stop the bleeding now. I have to use U.S. forces to help do that."
The fight in Afghanistan is complicated by the fact that insurgents have a safe haven across the Pakistan border. Pakistan is carrying out its own battle with the Taliban, but is unwilling to allow the U.S. to enter Pakistan to chase al Qaeda or Taliban fighters.
Keane said the two battlefields are "inextricably linked together" and "you can not lose in Afghanistan and hope to win in Pakistan."
But Clark, former NATO Supreme Allied commander and the general who oversaw the U.S. war effort in Kosovo, told "GMA" today that there is no reason for Obama to rush.
"I don't think he has to make this decision tomorrow," he said. "Get the American people behind it, get our allies behind it."
"I'm saying we better be sure we're doing whatever it takes. And it's really about al Qaeda, not Afghanistan," Clark said.
Clark said the U.S. government would be wise to remember the lessons learned in Vietnam. More U.S. troops mean more casualties, "and that reduces public support even faster."
And like Vietnam, the enemy has a sanctuary across the border safe from U.S. troops, and Americans cannot expect to the Afghan government to look like American democracy. "Those are three clear lessons from Vietnam," said Clark.