The war on terror took a decisive turn in 2003, beginning with the looming prospect of war with Iraq and ending with the capture of dictator Saddam Hussein (search).
In between was a series of events that defined an eventful and emotional year.
The most visible aspect of the war on terror began with Secretary of State Colin Powell (search) appealing to the United Nations to enforce its Security Council resolutions against Saddam's regime.
"Today, Iraq still poses a threat and Iraq still remains in material breach," Powell told the Security Council in early February.
After months of diplomatic haggling, the U.S. was unable to sway permanent member holdouts France, Russia and China. As a result, the United States, Britain and a coalition of more than 35 nations issued a final warning to the Iraqi dictator.
"All the decades of deceit and cruelty have now reached an end. Saddam Hussein and his sons must leave Iraq within 48 hours," Bush said in a March 17 address to the nation.
Saddam's failure to accept the ultimatum sealed the fate of his regime.
"On my orders, coalition forces have begun striking selected targets of military importance to undermine Saddam Hussein's ability to wage war," Bush told the nation two days later as explosions rocked Baghdad.
The opening shots of Operation Iraqi Freedom (search) concentrated on a "target of opportunity" in the heart of Baghdad -- an attempt to decapitate the Iraqi government on the first night of the war.
But after a few hours, a pre-recorded message from a disheveled-yet-defiant Saddam aired on Iraqi television. He vowed to "conquer the invaders" and win with the help of Allah.
The threat didn't deter the Pentagon. It had its own message for Saddam -- this war will be like no other.
"It will be of a force and scope and scale that has been beyond what has been seen before," Defense Secretary Donald Rumsfeld (search) said.
The "shock and awe" campaign ensued two days into the campaign with a massive air offensive that targeted Iraq's command and control structure. At the same time, ground troops rapidly rolled through the country toward Baghdad.
Journalists given unparalleled access to the battlefield documented the advance with live pictures. Fox News correspondent Greg Kelly accompanied the 3rd Infantry Division into Baghdad on April 7, just 19 days into the conflict.
Two days later, Iraqis expressing their opinions in a way they never could under Saddam Hussein, provided some of the most memorable images of the war -- banging on a statue of Saddam until at last the U.S. military helped to pull down literally the fallen dictator.
Forty-five days after the start of the war, on May 1, President Bush landed aboard the aircraft carrier USS Abraham Lincoln to issue a steady declaration.
"Major combat operations in Iraq have ended," he told sailors returning from the region.
With that announcement came the most challenging task for coalition forces -- guarding against foreign fighters and terrorists attacking U.S. and coalition forces in Iraq.
In Najaf, terrorists blew up a mosque killing 85 people, including a respected Shiite cleric. A suicide bomber penetrated security at the United Nations headquarters in Baghdad, killing the U.N. envoy to Iraq.
Outside Fallujah, insurgents shot down a Chinook helicopter, killing 15 and injuring 21 U.S. troops in the deadliest attack on U.S. forces since the declared end of major combat.
Also in Baghdad, Deputy Defense Secretary Paul Wolfowitz (search) made a narrow escape after rockets were fired at his hotel.
Despite the dangers, Hussein sons Uday and Qusay were killed in a shootout with U.S. forces in July. Video of their bodies gave proof to Iraqis that the regime was finished.
In December, Saddam was captured alive in his hometown of Tikrit, found hiding in a vermin-infested spider hole the size of a coffin.
The former Iraqi dictator offered to negotiate with the U.S. troops that captured him, but they merely sent regards from President Bush. The president then sent a message to any remaining Saddam loyalists.
"There will be no return to the corrupt power and privilege they once held," Bush said.
With Iraq designated as the central front in the war on terror, coalition troops are now attempting to secure the country and make way for an Iraqi-led democratic government.
In the original front of the war on terror, Afghanistan, 11,000 U.S. troops continue the fight against Taliban and Al Qaeda remnants, engaging in several operations aimed at pounding mountain hideaways where fighters are believed to be taking refuge.
Meanwhile, Taliban and Al Qaeda forces are adapting to the new Afghanistan -- reforming their tactics by taking aim at soft targets such as relief workers. Eleven aid workers were killed in 2003.
Even as combat continues, reconstruction is under way in the war-torn country. The so-called Ring Road will eventually link the northeastern city of Kabul to Herat in the west and Kandahar in the southeast.
In August, NATO forces took over security in Kabul. They now lead a multi-national force of about 20 NATO and partner nations. The new forces have relieved other countries from the task of six-month rotations leading the troops there.
One of the most telling signs of progress in Afghanistan is the emergence of the Afghan national army. The first unit went on patrol in Februrary, and others are fighting jointly alongside American-led forces. It was a huge step toward having Afghan troops provide their own country with an independent fighting force.
But still believed to be lying low somewhere along the Afghan-Pakistani border is Usama bin Laden (search). Last seen in September on a tape aired on Al Jazeera television, bin Laden made references to recent events including the Iraq war.
Believed to be authentic although the video apparently was several months old, the audio confirmed to intelligence officials that the Al Qaeda leader is most likely still alive.
The number three Al Qaeda figure, Khalid Sheik Mohammed (search), was captured in Pakistan in March. Mohammed is in U.S. custody, being questioned overseas.
In the United States, the intense security is a constant reminder that the war on terror, waged at home and abroad, continues into the new year.