US President George W Bush has arrived in Afghanistan on a surprise visit, his last before stepping down in January. Mr Bush addressed US troops at Bagram air base before leaving for talks with his Afghan counterpart, Hamid Karzai. He said Afghanistan was a "dramatically different country than it was eight years ago", when US-led forces invaded.President Bush was met at Bagram air base, north of Kabul, early on Sunday by Gen David McKiernan, the US commander of Nato-led troops in Afghanistan. He was then led into a giant white tent, where hundreds of US troops greeted him with cheers as he thanked them for serving.
"I am confident we will succeed in Afghanistan because our cause is just," he said in a speech. "Afghanistan is a dramatically different country than it was eight years ago," he added. "We are making hopeful gains."
Mr Bush said he recognised that more troops were needed in the country and that he supported President-elect Barack Obama's pledge to increase numbers. He also said it was important to continue working with Pakistan so that pressure was kept on militants based along its border with Afghanistan. "If Pakistan is a place from which people feel comfortable attacking infrastructure, citizens, troops, it's going to make it difficult to succeed in Afghanistan," he said. "The more we can get Pakistan and Afghanistan to co-operate, the easier it will be to enforce that part of the border regions."
Speaking on Air Force One en route to Afghanistan, Mr Bush told reporters that his country's goal there was similar to the one in Iraq - to let the new democracy develop its institutions so that it could survive on its own. "The degree of difficulty is high. It's hard. Nevertheless the mission is essential," he said. "We cannot… achieve our objective of removing the safe havens, kicking out the Taleban, and say: 'OK, now let's leave'," he added.
While visiting Baghdad on Saturday, Mr Bush said the war in Iraq was not yet over and that much work still needed to be done there. "The work hasn't been easy but it's been necessary for American security, Iraqi hope and world peace," he said during talks with President Jalal Talabani.
The Iraqi leader called Mr Bush "a great friend for the Iraqi people, who helped us liberate our country".
Later, Mr Bush signed a security pact with Prime Minister Maliki which calls for US troops to be withdrawn from Iraq by the end of 2011. They are first to withdraw from Iraqi cities by June next year.
The BBC's Sarah Morris in Washington says the presidential trip to Iraq and Afghanistan was planned with meticulous secrecy. The accompanying journalists were asked to tell no-one other than a superior and their spouse. The White House even published a false schedule of events.