The U.S.-led assault on Iraq began today just as the new dawn was breaking over Baghdad.
The first salvo in "Operation Iraqi Freedom" was a barrage of about 40 Tomahawk cruise missiles and attacks by F-117 stealth fighters dropping precision-guided bombs against a "target of opportunity" near Baghdad, believed to include high-ranking Iraqi leaders, U.S. officials said.
"On my orders, coalition forces have begun striking selected targets of military importance to undermine Saddam Hussein's ability to wage war," President Bush said in a 10:15 p.m. ET address to the nation.
Coming about 90 minutes after Bush's deadline for Saddam Hussein to leave Iraq expired, the attack was not the start of the massive "A-Day" air assault planned by the United States and its coalition to "shock and awe" Iraqi forces into submission, officials said.
The early attack was launched because the United States had intelligence that "very senior leadership" of Iraq was in one place, sources told ABCNEWS.
Because it was "not part of the plan," U.S. officials now are keeping an eye on the Iraqi response to see if they have to accelerate the original A-Day plan, a senior military official said.
In Baghdad, air raid sirens began howling just before daybreak, around 5:30 a.m. local time (9:30 p.m. ET), followed by about 10 minutes of anti-aircraft fire, according to ABCNEWS' Richard Engel.
Later, another series of explosions could be heard outside the city, and subsequent bursts of explosions erupted periodically.
It was unclear exactly what the missiles hit, but sources described the target as a residence in the southern part of the city. U.S. intelligence was trying to assess the results of the attack.
However, after the initial attacks, Saddam Hussein's son Odai reportedly spoke on Iraqi radio, saying, "God bless Saddam and God protect Iraq" — though it was unclear if the message was live or taped.
First official U.S. confirmation of the attacks came from White House press spokesman Ari Fleischer at around 9:45 p.m. ET.
"The opening stages of the disarmament of the Iraqi regime have begun," Fleischer told reporters, before walking away from the podium.
Sources said the president decided between 6:30 p.m. and 7:20 p.m. ET, during his third war council meeting of the day, to launch the attack. Afterward, he met briefly with his speechwriter, Michael Gerson, and then headed to the White House residence for dinner.
Soon after his evening announcement of the attacks, Bush was said to have gone to sleep for the evening.
On Monday, Bush gave the Iraqi president and his sons, Odai and Qusai Hussein, 48 hours, ending at 8 p.m. ET tonight, to leave the country or face military action.
Bush's nationally televised ultimatum brought to an end six months of frantic diplomacy at the U.N. Security Council, with France leading the call to give U.N. arms inspectors in Iraq more time to complete the disarmament process.
At a Security Council meeting before the attacks began, France, along with Russia and Germany, once again spoke out against a war with Iraq.
Addressing the Speaking Council just hours before the end of Bush's 48-hour ultimatum, Russian Foreign Minister Igor Ivanov said his country would help the war effort, "if today, we really had indisputable facts demonstrating that from the territory of Iraq there was a direct threat to the United States."
But no proof had been produced, Ivanov said, and the authority of the United Nations had been superceded.
Despite the lack of U.N. approval and widespread opposition to the war in the Muslim world, the Bush administration has maintained that there was an international "coalition of the willing" backing a war. Earlier this week, Secretary of State Colin Powell released a list of 30 nations that had joined that group.
International opposition to the war in recent months has centered around doubts about the Bush administration's rationale for launching "pre-emptive strikes" against Iraq.
In November 2002, U.N. weapons inspectors returned to Iraq after a four-year absence, when the Security Council unanimously voted Resolution 1441 granting Iraq a "final opportunity to comply with its disarmament obligations."
But Washington's efforts to get a new resolution authorizing the use of military force passed by the Security Council proved to be an uphill diplomatic challenge, with France threatening to veto any new resolution.
The diplomatic effort was eventually abandoned on Monday, when Britain's U.N. ambassador, Jeremy Greenstock, announced that Britain and the United States would not submit a new U.N. proposal.
But even as a war of words raged in the corridors of the United Nations, the Pentagon had begun a massive military buildup in the region in recent months.
An estimated 300,000 troops, including British military personnel, backed by more than 1,000 warplanes, were placed in the region, for an attack before today's call to war. The troop buildup has been commandeered from a command center headquartered in Qatar.
The Bush administration has maintained that the Sept. 11, 2001, attacks on the United States had highlighted the potential threat to national and international security from individuals and nations amassing weapons of mass destruction.
But critics — including governments of countries on the Security Council — have questioned Washington's allegations that Saddam has links to the al Qaeda terror network, which the United States holds responsible for the Sept. 11 attacks.
And the Iraqi government has repeatedly maintained that it does not possess banned weapons of mass destruction, a claim Washington and London rejects.
On Monday, in a speech that marked the culmination of the rupture between America and the United Nations, Bush condemned the international organization's failure to sanction a war with Iraq.
"The United Nations Security Council has not lived up to its responsibilities," Bush said. "So we will rise to ours."
Bush however gave the Iraqi president two days to flee or face the might of the U.S. military.
It was an ultimatum that Saddam rejected the very next day after a rare television appearance on Iraqi state television. In a statement broadcast across the nation, the Iraqi Cabinet said, "Iraq and all its sons were fully ready to confront the invading aggressors and repel them."
ABC News' Michael S. James and Bryan Robinson contributed to this report.