US President George W. Bush arrived in Belfast, Northern Ireland, for the third meeting in as many weeks with his closest ally in the war, British Prime Minister Tony Blair.

The US military said the assault on central Baghdad by over 100 tanks and armored vehicles was a show of force, rather than a final attack on the sprawling city of five million.

Maj. Michael Hamlet of the US 101st Airborne Division said earlier that initial tests on substances found at a military training camp in central Iraq revealed levels of nerve agents sarin and tabun and the blister agent lewisite.

“If tests from our experts confirm this, this could be the smoking gun. It would prove Saddam has the weapons we have said he has all along,” Hamlet said.

In what appeared to be a separate incident, US National Public Radio reported US forces near Baghdad found a cache of 20 medium-range missiles equipped with potent chemical warheads.

Citing a top official with the 1st Marine Division, NPR said the BM-21 missiles were equipped with sarin and mustard gas and were “ready to fire.”

Battles flared near Baghdad’s landmark Al-Rashid Hotel after US forces sped in from the west and southeast to assault potent symbols of Saddam’s 24-year rule.

Iraqi paramilitary fighters fired assault rifles and rocket-propelled grenades toward the Al-Rashid area but it was not clear who was returning fire because Iraqi forces had cordoned off the area.

At least 14 civilians were killed, including nine members of one family, when a bomb crashed into the Al-Mansur residential district of the capital, witnesses said.

Throughout the day, hospitals battled with a constant stream of civilian dead and injured. Doctors said they were running short of anesthetics and medical equipment.

At the Kadhimiya Hospital in the north of the city, doctors said they had taken in 18 dead and 142 injured in two days, while the central Kindi Hospital had four dead and 176 injured.

“Surgeons have been working round the clock for the past two days and most are exhausted. Conditions are terrible,” said Roland Huguenin-Benjamin, local spokesman for the International Committee of the Red Cross.

A US armored column, backed by fighter jets, blasted into central Baghdad early yesterday, meeting only light resistance, but two Marines were killed and three wounded in a fierce battle for two river bridges in the east. Marines said their comrades died in “friendly fire” when an artillery shell fired by their own side fell short.

The Marines later crossed the Diyala River even though the Iraqis had damaged the bridges to slow them up. Two US soldiers and two journalists were killed and 15 people wounded in an Iraqi attack on a communications center in the southern outskirts of the capital, military sources said.

US officers described the incursion on the war’s 19th day as a tactical raid, not the start of a final battle to seize the capital.

“This does not represent the battle for Baghdad. What this is is a powerful message that we can go where we want, when we want,” Department of Defense spokesman Maj. Ben Owens said.

As part of the “message” a tank blew a huge statue of Saddam off its pedestal in central Baghdad, US military officials said.

The Iraqi government remained defiant, dismissing international footage of US tanks rolling down the western bank of the Tigris River.

“Don’t believe these invaders and these liars,” a smiling Iraqi Information Minister Mohammed Saeed Al-Sahaf told an impromptu press conference.

“They pushed forward some troop transporters and tanks. We have surrounded them with our troops. We will massacre them, these invaders,” Sahaf said.

Iraqi state-run television showed Saddam chairing a meeting of top military and political brass, including his son Qusay, the head of the elite Republican Guards. A military spokesman said on state television that Iraq had shot down two US military planes around Baghdad.

The Baghdad raid saw US tanks and fighting vehicles push toward the western bank of the Tigris. They captured two of Saddam’s palaces in the city center and a third near the airport, according to Lt. Col. Peter Bayer, the 3rd Infantry Division’s operations officer. “There are two palaces (in the city center), we own both of them ... (but) we’ve been significantly challenged,” Bayer said.

US Marines entered Baghdad from the southeast despite the fact that Iraqi forces blew up two bridges on the Diyala River, which runs east of the Iraqi capital.

In the south of the country, British troops poured into the country’s second largest city, Basra.

“The battle is more or less over now,” Lt. Col. Hugh Blackman of the 7th Armored Brigade said. “We are covering all the areas of Basra, including the old city.”

Britain’s defense secretary said there was strong evidence that Ali Hasan Al-Majid — a senior Saddam aide known as “Chemical Ali” for allegedly ordering gas attacks that killed thousands of Kurds in 1988 — had been killed in a US-British airstrike three days earlier.