BAGHDAD-A timeline of key events in Iraq, beginning with the U.S.-led invasion to the March 7 parliamentary elections:

March 20: The U.S.-led invasion is launched.

April 9: American Marines help Iraqis pull down statue of Saddam Hussein in Baghdad.

May 1: On an aircraft carrier under a "Mission Accomplished" banner, President Bush declares major combat operations in Iraq over.

May: L. Paul Bremer, the top U.S. administrator in Iraq, issues de-Baathification decree barring thousands from Saddam's Baath Party from government jobs and disbands Iraqi Army.

MARJA, Afghanistan - As American Marines and Afghan soldiers have fought their way into this Taliban stronghold, the performance of the Afghan troops has tested a core premise of the American military effort here: in the not-too-distant future, the security of this country can be turned over to indigenous forces created at the cost of American money and blood.

Scenes from this corner of the battlefield, observed over eight days by two New York Times journalists, suggest that the day when the Afghan Army will be well led and able to perform complex operations independently, rather than merely assist American missions, remains far off.

DELARAM, Afghanistan -- American Marines came under attack by Taliban fighters Monday at the start of an operation intended to push insurgents from a volatile town in southern Afghanistan, while across the country six Western service members, including at least three Americans, were killed in battle.

The toll amounted to the deadliest day in more than two months for international forces, at a time when thousands of additional Marines are arriving as part of President Obama's troop buildup in Afghanistan.