Events at a Glance

HOME FRONT

Attack warning: The Bush administration again urged Americans to beware of new terrorist attacks, saying the danger is particularly high during the holidays.

Border security: The United States and Canada announced a plan to tighten security along their 4,000-mile border.

Anthrax: Tens of thousands of letters mailed around the country could have picked up trace amounts of anthrax while passing through a contaminated Trenton, N.J., postal facility, the nation’s top anthrax investigator said.

American jihadi: The father of a Marin County man who was captured with Taliban forces says his son was a devout but peace-loving Muslim. San Francisco energy lawyer Frank Lindh said John Walker, 20, was raised as a Catholic but converted to Islam at 16 after reading “The Autobiography of Malcolm X.”

AFGHAN FRONT

Airstrikes: Facing questions about scores of alleged civilian deaths, Pentagon officials said they will launch a new investigation of the bombing of Tora Bora, a complex of caves and tunnels where terrorist leaders are believed to be hiding.

DIPLOMACY

Powell: In a hastily arranged effort to mend diplomatic fences, the Bush administration dispatched Secretary of State Colin L. Powell to confer with European allies.