American missiles fell on Baghdad for the second straight night Thursday and ground troops attacked Iraqi forces in the desert with artillery in a slow escalation of the war to drive Saddam Hussein from power. Iraqi missiles fell harmlessly in Kuwait.Half a world away from the war theater, U.S. intelligence officials sought to determine whether the Iraqi leader had been killed hours earlier in a pre-dawn attack by cruise missiles and precision-guided bombs.

State-run television denied it, and said the Iraqi dictator had met with aides during the day.

Either way, said Defense Secretary Donald H. Rumsfeld, "The days of the Saddam Hussein regime are numbered."

He called on Iraqi leaders to surrender - and said the alternative was an attack "of a force and scope and scale that has been beyond what has been seen before."

With more than 250,000 troops, 1,000 combat aircraft and a naval armada in the Persian Gulf region, administration officials said the full-scale invasion was just over the horizon.

In the capital, red and white anti-aircraft tracers lit the night sky and a huge plume of smoke rose into the night from the west bank of the Tigris River in central Baghdad.

A senior defense official with direct knowledge of the operation said the attack included sea-launched cruise missiles fired at Republican Guard strongholds in Baghdad.

But two officials, speaking on condition of anonymity, said the night strikes were not the beginning of the massive air assault that Pentagon plans to unleash.

In southern Iraq , white light glowed in the desert sky, and the sound of explosions could be heard from across the Kuwait-Iraq frontier as the 3rd Infantry division unleashed its artillery barrage. Troops eager to cross the border into Iraq cheered.

Iraq sent its missiles toward Kuwait in retaliation for the pre-dawn attack against Saddam.

Inside Iraq, flames shot skyward from the area of the southern oil center of Basra, and American military officials told reporters that three or four oil wells had been set ablaze.

Iraq lit fires at Kuwait's oil fields as it withdrew its forces in the 1991 Persian Gulf war , and Pentagon officials have expressed fears that the this time, the regime could order the destruction of its own wells.

In the Kuwaiti desert, officials said none of the Iraqi missiles caused injuries, and one was intercepted by a Patriot missile. Thousands of American and British troops donned protective gear, but there was no evidence the missiles carried chemical or biological weapons.

The onset of war sparked large anti-war demonstrations at U.S. embassies around the world, and the State Department warned U.S. citizens abroad of an increased danger of terrorism.

In Washington, protesters briefly blocked one of the Potomac River bridges carrying traffic into the capital. Outside the White House, demonstrators shouted "no blood for oil."

But inside the executive mansion, President Bush met with his advisers, and from the commander in chief down through the chain of command, officials made clear they were operating on their own timetable.

Bush was in the Oval Office before 7 a.m. EST, and summoned his Cabinet to a mid-afternoon meeting to discuss the war.

The president approved the cruise missile attack on Wednesday night after receiving intelligence information that Saddam and his two sons were sleeping at a specified location, according to officials.

Iraqi Information Minister Mohammed Saeed al-Sahhaf said one person was killed and doctors said 14 were injured in the attack.

Hours later, Shabab television, owned by Saddam's son Odai, reported that the Iraqi leader met with his top aides to "review military and other measures to resist the aggression."

But American intelligence officials scrutinized videotape of a televised speech broadcast after the attack to see whether the man shown was Saddam, or perhaps a double.

Asked whether officials believe the puffy-faced man on the tape was the Iraqi leader, Rumsfeld said, "There's debate about that."

Other officials, who spoke to The Associated Press only on condition of anonymity, said there was growing optimism the strike had left the Iraqi leadership in disarray.

Early intelligence reports suggested Iraq's leadership was not organizing any coordinated response to the U.S attack, suggesting the Iraqi regime might be in chaos or cut off from the military, these officials said.

In addition to the strikes that were visible in Baghdad on Wednesday night, the commander of one of five U.S. aircraft carriers in the region said warplanes under his command flew 54 overnight sorties.

Rear Adm. Barry Costello, commander of the USS Constellation, also said some were aimed at "military installations and communications facilities" in Iraq.

The strikes were part of a "transition period" in which U.S. planes "continue to prep the battlefield, to clear a path for further air strikes and ground operations," Costello said.

PHOTO CAPTION

American and British troops and journalists take shelter Thursday March 20, 2003, in 'Scud trenches' during an unconfirmed Iraqi missile attack in the Kuwaiti desert. (AP Photo/MoD Pool, Dan Chung, The Guardian)