One of the many huge explosions that rocked the Iraqi capital on Friday

The U.S. and its allies launched a massive aerial assault against Iraq on Friday. At 12:15 p.m. EST, anti-aircraft fire could be seen rising in the skies above Baghdad. Within an hour, tremendous explosions began rocking the Iraqi capital, as the Pentagon announced "A-Day" was underway.

The campaign was intended to instill "shock and awe" among Iraq's leaders, and it was directed at hundreds of targets in Iraq, officials said. Plumes of fire could be seen rising above targets in Baghdad at 1:05 p.m. EST. CNN Correspondent Wolf Blitzer reported that in his 30 years of experience, he had never seen anything on the scale of Friday's attack on the Iraqi capital.

The attack was not limited to Baghdad. Targets were struck in Mosul, Iraq's second-largest city, which lies in the north of the country. And anti-aircraft fire lit up the sky over the southern city of Kirkuk as well.

Defense Secretary Donald Rumsfeld held a news conference at about 1:40 p.m. EST. He announced that the air war had begun, and he listed some of the coalition objectives in Operation Iraqi Freedom. Those objectives included defending Americans against Iraq's alleged weapons of mass destruction, ridding the Gulf country of such illegal weapons, liberating the Iraqi people, and ending the regime of Iraqi President Saddam Hussein.

SPECIAL REPORT •  War Tracker •  On the Scene Map •  Commanders: U.S. | Iraq •  Weapons: 3D Models •  Coalition casualties | POW/MIA •  Special Report • CNN.com: Massive firestorm targets Iraqi leadership  • CNN.com: War Tracker  • CNN.com: Special: War on Iraq  • Timeline: The first nine hours  • Gallery: War on Iraq   • Holt, Rinehart and Winston: Conflict in the Persian Gulf

Rumsfeld said that the strike had taken place "on a scale that indicates to Iraqis" that Saddam and his leadership were finished. He added that the allies would work to search for, capture, and drive out terrorists who had found safe harbor in Iraq, as well as to deliver humanitarian relief to the Iraqi people.

Iraqi leaders are "starting to lose control of their country," Rumsfeld announced on Friday. He added that the confusion among Iraqi generals was growing, and he speculated that those close to the Iraqi leader would question where they stood in terms of their support for Saddam.

Rumsfeld also advised Iraqi military officials not to obey orders to use weapons of mass destruction, not to use innocent people as human shields around military forces or equipment, and not to destroy oil wells or blow up dams. He said that those who did not follow this advice would be punished.

The full-scale strike came just days after Iraqi President Saddam Hussein defied a 48-hour deadline to leave the country, which President Bush imposed on March 17. Operation Iraqi Freedom comes as a coalition effort to force Baghdad to disarm.

Warning of the attack

When Iraq lost the 1991 Gulf War, the country agreed to peace terms with the coalition that defeated Baghdad. However, it did not always cooperate with those terms. For example, Iraq was required to allow U.N. weapons inspectors ensure the country was not rebuilding certain types of arms. But Iraq kicked the inspectors out of the country in 1998, and they did not return until the U.N. passed Resolution 1441 last year.

Resolution 1441 demanded that Iraq give up its alleged weapons of mass destruction. The measure threatened "serious consequences" if Iraq did not disarm.

RESOURCES • Interactive: Council on Iraq • Latest: Iraq Tracker • Explainer: Al Samoud • Special Report: Showdown Iraq

The U.S., Britain, and Spain introduced a newer resolution to the United Nations on February 24. It stated that Iraq was in "material breach" of Resolution 1441 - language that could have led to the U.N.'s involvement in the current strike. However, the U.N. did not pass the measure. So the current strike against the Gulf nation comes without the full support of the U.N. - a move President Bush had insisted the U.S. and its allies would make, if necessary.

The framers of the U.S. Constitution gave Congress the power to declare war, but they made the president the commander-in-chief of the armed services. Under the War Powers Act passed by Congress in 1973, the president must consult with Congress before deploying the U.S. military in "hostilities."

Historically, U.S. presidents have not always followed the requirements of the War Powers Act, and Congress for the most part has not enforced it. But President Bush did seek congressional approval for a potential strike in October 2002. At that time, the House and Senate both authorized the president to attack Iraq if Saddam refused to abide by U.N. resolutions.

The War Powers Act also requires President Bush to report to Congress every 60 days on military operations. The White House also must update lawmakers on planning for "post-military" operations in Iraq, which could include efforts to keep the peace in Iraq and help rebuild the Gulf country after the war is over.