Obama in a 13-minute national address Wednesday announced plans to withdraw 10,000 troops from Afghanistan by the end of the year. Another 20,000 troops committed in a December 2009 troop surge are to leave by next summer. There would be about 70,000 U.S. troops in Afghanistan after that.
NATO Secretary-General Anders Fogh Rasmussen in a statement said Obama's decision was a sign of progress on the ground in Afghanistan.
"We can see the tide is turning," he said. "The Taliban are under pressure."
The United Nations announced it was taking measures that would give Afghanistan room to incorporate moderate members of the Taliban in the political process as part of reconciliation and reintegration process.
Afghan President Hamid Karzai has said he'd like his forces to assume responsibility over security operations by 2014.
U.S. defense contractor Raytheon announced Thursday that the first 16 students from the Afghan air force completed a training program in Virginia.
"The Afghan security forces are getting stronger every day," added Rasmussen.
Critics of Obama's plan complained about the finer points of the redeployment.
"We shouldn't adhere to an arbitrary timetable on the withdrawal of our troops from Afghanistan," Republican presidential hopeful and former Massachusetts Gov. Mitt Romney said in a statement.
Obama promised when he committed to the surge to start returning the troops to the United States within 18 months.