The Taliban has issued a chilling warning to America and its allies, vowing to 'defend its homeland and continue to fight any 'invaders', just as memorials got underway to mark the 11th anniversary of the terror attacks.

Almost 3,000 people were killed when the Twin Towers in New York, along with buildings in Washington and Pennsylvania were hit by hijacked planes. In return the US waged a war against al-Qaeda and the Taliban who were close allies.

At The White House today President Barack Obama and his wife Michelle observed a minute's silence in memory of the victims.

Meanwhile in the capital of Afghanistan coalition troops took time out of their duties to hold a memorial service. US Deputy Commanding General, Brigadier Ricky Gibbs reminded fellow soldiers that they are there to ensure the country quote 'never again becomes a safe haven for terrorists. And that their Afghan and NATO partners share the same focus and commitment."

Violence in the country is still very much on the agenda. The Taliban confirmed to the Reuters news agency that they fired four rockets at a helicopter destroying it as it sat on a ramp at the NATO Bagram airfield in Kabul last night. Three Afghan army personnel who were inside the chopper died.