LONDON, England (CNN) -- Presumptive Republican presidential nominee John McCain said Thursday the current problems in Iraq stem from a mishandling of the war after its initial success.
McCain spoke after his meeting with British Prime Minister Gordon Brown, which coincided with the fifth anniversary of the U.S.-led invasion of Iraq.
"The problem with Iraq, in my view, is that it was mishandled after the initial success," said McCain, who visited Iraq earlier this week.
McCain said the troop "surge" was working, and he said it is important to see the U.S. strategy in Iraq "through to success" because the work there is not over.
"Having just come from Iraq, I can tell you unequivocally that the situation has improved dramatically over the last year. Iraqi people are going about their normal lives," McCain said. "But the fact is, al Qaeda is on the run. They are not defeated."
McCain said withdrawal would only allow al Qaeda to declare victory and would lead to a "collapse" in the Gulf nation.
The senator said he also discussed climate change and Tibet with the British leader.
"I'm convinced that if we work at it, that we will be able to convince India and China that it is in their interest to be part of a global agreement to reduce greenhouse gas emissions," McCain said. "We will not have a global agreement that is effective unless India and China are a part of it."
On Tibet, McCain said he was "very disturbed" about events there and how China had handled the situation.
"I strongly urge them to respect the rights of the people who are demonstrating there," McCain said. "There's a long history of Chinese treatment of the people in Tibet which is certainly not one that I think the Chinese should be proud of, and I hope that they would quickly respect the human rights of the people there."
It was McCain's first meeting with Brown since the Labour Party leader became prime minister last year.
CNN's European Political Editor Robin Oakley said the planning the trip was a wise strategic move on the Senator's part.
"It's a wonderful opportunity for a would-be US president to put himself about in foreign countries and show he's a world statesman, particularly at a time when the Democrats are still squabbling among themselves."
It was also important for European leaders like Brown to receive him as they may have to deal with him as a President in the future, Oakley said.
McCain said he was visiting not as a campaigning presidential candidate but as the top Republican on the Senate Armed Services Committee.
Joining McCain were Republican Sen. Lindsey Graham and Democrat-turned-independent Sen. Joseph Lieberman, who are also members of the committee. All three men are outspoken advocates of the surge strategy, under which additional American troops were sent to Iraq last year. E-mail to a friend