The Associated Press

U.S. warplanes attacked Baghdad's defenders with bombs and strafing fire Saturday in a thunderous prelude to a ground assault. Iraqis inflicted a new danger on the allies -- a deadly suicide attack -- and threatened to kill Americans on U.S. soil.

Anger, mourning and resolve emanated from both sides in a conflict taking a growing toll each day in the lives of combatants and civilians alike.

The international outcry grew, too. Pope John Paul II warned of a "religious catastrophe" stirring hatred between Christians and Muslims; Russian President Vladimir Putin also cast the war in catastrophic terms and said he would push for a negotiated solution.

But in Baghdad, Washington and along the war's many fronts, the talk was all of climactic battles to come.

"We are now fighting the most desperate units of the dictator's army," President Bush said before an hourlong meeting with his war council and an intelligence briefing.

Three-quarters of the allied airstrikes are now going after Republican Guard forces ringing Baghdad, Air Force Brig. Gen. Daniel Darnell told The Associated Press.

He said U.S. and British planes have attacked almost every military airfield in the country in the last week.

Danger came to the 1st Brigade of the Army's 3rd Infantry Division in the guise of a cab driver.

A man, identified by Iraqi officials as a noncommissioned officer, drove his taxi to a U.S. checkpoint in south-central Iraq and waved for help. When soldiers approached, the car exploded and four Americans died.

"It looks and feels like terrorism," Maj. Gen. Stanley McChrystal said at the Pentagon. "It won't change our overall rules of engagement but, to protect our soldiers, it clearly requires great care."

More than 30 U.S. soldiers have died in the war.