WASHINGTON —  President Bush, trying to defend his war strategy, declassified intelligence Tuesday asserting that Usama bin Laden ordered a top lieutenant in early 2005 to form a terrorist cell that would conduct attacks outside Iraq — and that the United States should be the top target.

Frances Fragos Townsend, the White House homeland security adviser, said the intelligence bolsters the Bush administration's contention that Al Qaeda wants to use Iraq as a staging area to launch terrorist attacks around the world, including the United States.

In January 2005, bin Laden tasked Al Qaeda operative Abu Musab al-Zarqawi, who was in Iraq, to organize the cell, Townsend said. Al-Zarqawi, the former leader of Al Qaeda's Iraq operations, was killed there in June 2006 by a U.S. airstrike.

"We know from the intelligence community that al-Zarqawi welcomed the tasking and claimed he already had some good proposals," Townsend said.

She said that in the spring of 2005, bin Laden instructed Hamza Rabia, a senior operative, to brief al-Zarqawi on Al Qaeda planning to attack sites outside Iraq, including the United States. She did not disclose where in the United States those attacks were being plotted.

Around the same time, Abu Fajah al-Libi, a senior Al Qaeda manager, suggested that bin Laden send Rabia to Iraq to actually help al-Zarqawi plan the external operations, Townsend said. It is unclear whether Radbia went to Iraq, she said.

She said the information was declassified because the intelligence community has tracked all leads from the information.

Townsend disclosed the information to The Associated Press and other news agencies in advance of Bush's commencement speech Wednesday at the U.S. Coast Guard Academy. Bush is expected to emphasize the continuing threat of terrorism and recount steps taken by his administration to prevent attacks.