British submarines launched cruise missiles at Afghanistan this afternoon, joining the United States in its military retaliation for last month's attacks on New York and Washington. Prime Minister Tony Blair told reporters that Germany, France, Australia and Canada had committed themselves, along with Britain, to take part in the U.S.-led action. Blair was speaking at his Downing Street residence shortly after U.S. President George W. Bush announced that military strikes on Afghanistan had begun. I can confirm that UK forces are engaged in this action, he said. Blair, who is Bush's staunchest ally in Washington's war on terrorism, said military action was directed against training camps of Osama bin Laden's al Qaeda network in Afghanistan and military facilities of the country's Taliban rulers. He said almost a month had passed since suicide hijackers destroyed the World Trade Center in New York and hit the Pentagon near Washington, and more than two weeks since the Taliban was given an ulitmatum to hand over bin Laden, Washington's chief suspect. Blair said he had no doubt that bin Laden was to blame for the attacks on the United States on September 11. This military plan has been put together mindful of our determination to do all we humanly can to avoid civilian casualties, he said. I cannot disclose obviously how long this action will last. We will act with reason and with resolve. Blair's announcement came as witnesses in Afghanistan reported that a series of explosions had lit up the night sky over Kabul. Other reports said the cities of Jalalabad and Kandahar were also under attack. We have set the objectives to eradicate Osama bin Laden's network of terror and to take action against the Taliban regime, Blair said. Last Wednesday, the United States government made a specific request that a number of UK military assets be used in the operation which has now begun and I gave authority for these assets to be deployed. Iain Duncan Smith, leader of Britain's opposition Conservative Party, said he supported a third emergency recall of parliament at the earliest opportunity, something the government is believed to be planning. He expressed his backing for Blair's decision to join the military action.