The targets included European tourist resorts frequented by Americans, as well as US military bases, embassies and consular offices in Europe.

"Today's guilty plea brings an end to the long, dangerous career of Christopher Paul, an Ohio native who joined Al-Qaeda in the early 1990s, fought in Afghanistan and Bosnia and conspired with others to target Americans both at home and abroad," said Acting Assistant US Attorney General Patrick Rowan, on Tuesday.

"His conviction demonstrates our continuing resolve to protect the American public against terrorism."

Paul, 44, was arrested in April 2007 on charges of providing material support to terrorists and conspiring to use a weapon of mass destruction.

He agreed to a sentence of 20 years in prison in exchange for having two of the three charges dropped during a change of plea hearing at an Ohio court yesterday.

"This guilty plea is a significant step forward in the war on terror," said US Attorney Gregory Lockhart.

In a statement of facts read during the hearing, Paul admitted that he travelled to Pakistan in the early 1990s to join the mujahedeen (Islamic fighters) and was trained by Al-Qaeda to fight in Afghanistan.