British Prime Minister Gordon Brown will use a speech Monday to defend the unpopular war in Afghanistan, arguing that the campaign is preventing al-Qaida from making the country a safe haven.
Brown's office said the prime minister would use his annual foreign policy address at the Lord Mayor's Banquet in London to say that "more has been planned and enacted with greater success in this one year to disable al-Qaida than in any year since the original invasion in 2001."
Excerpts from the speech were released in advance.
Brown will say that al-Qaida - driven from Afghanistan to Pakistan after the fall of the Taliban - could return if international forces leave.
"We are in Afghanistan because we judge that if the Taliban regained power, al-Qaida and other terrorist groups would once more have an environment in which they could operate," he plans to say.
"So I vigorously defend our action in Afghanistan and Pakistan because al-Qaida is today the biggest source of threat to our national security - and to the security of people's lives in Britain," Brown will add.