WASHINGTON - Sen. Barack Obama said Tuesday that the addition of tens of thousands of combat troops to Iraq last year had significantly reduced violence in the country. But he said that positive developments there had not changed his mind about the need to pull troops from Iraq so the U.S. could focus more on the deteriorating situation in Afghanistan.

In an address in Washington that was the most detailed outline yet of his national security strategy, Obama said it was time to rapidly end the war in Iraq, which he opposed from the start, and to begin to address the resurgent al-Qaida and Taliban forces in Afghanistan and Pakistan, which he said posed a far greater danger to U.S. security.

Obama's likely Republican opponent for the presidency, Sen. John McCain, drew the opposite conclusion from events in Iraq. He said the success of the troop buildup, which he supported from the start, pointed the way toward victory in Iraq and Afghanistan.

"Today we know Senator Obama was wrong," McCain said at a town hall-style meeting in Albuquerque, N.M. "Senator Obama will tell you we can't win in Afghanistan without losing in Iraq. In fact, he has it exactly backwards. It is precisely the success of the surge in Iraq that shows us the way to succeed in Afghanistan."

In his address on foreign policy, Obama argued that the war in Iraq had distracted the U.S. from what he called the central front in the fight against terrorism, the lawless areas along the Afghanistan-Pakistan border where al-Qaida was regrouping under Taliban protection.

McCain said that both Iraq and Afghanistan were important battlegrounds and that the U.S. had the ability to fight in both places as long as it retained the will to do so. But on Tuesday, after saying for months that no additional forces were needed in Afghanistan, McCain changed course and advocated the deployment of an additional three brigades, or about 15,000 troops.

McCain painted Obama as naive and untraveled, and pointed to his own extensive experience in the military and the government. "I know how to win wars," said McCain, a former Vietnam prisoner of war.

Obama will make his first overseas trip as a presidential candidate this month. He is scheduled to visit Jordan, Israel, the Palestinian territories, Germany, France and England. He has also said he plans to travel soon to Iraq and Afghanistan.