The number of weekly attacks in Iraq has dropped from about 1,200 a week in June 2007 to about 200 a week now, a U.S. commander said Monday.

Army Lt. Gen. Lloyd J. Austin III, commander of Multinational Corps Iraq, told reporters via satellite from Baghdad that the military has also recorded a 70 percent decrease in roadside-bomb attacks and an 85 percent spike in the number of weapons caches coalition forces have found over the past year.

The statistics come as the last of the five additional combat brigades sent to Iraq last year as part of the surge strategy -- the 2nd Brigade, 3rd Infantry Division -- prepares to head home. The unit also led the initial charge into Baghdad in March 2003.

There are currently 146,000 U.S. troops in Iraq, including 15 combat brigades. Before the buildup began early last year, there were fewer than 135,000 U.S. forces there. The departure of the unit will lower U.S. troop levels there to roughly 142,000 U.S. troops by mid-July -- still 7,000 more than before the buildup began.

The unit's departure sets up pivotal U.S. election-year questions about how many more troops can come home this year, and whether the decline in violence can be maintained by the fledgling Iraqi security forces.

In other news, an American soldier was killed and five others were wounded Monday when they came under fire southeast of Baghdad, the U.S. military said. Witnesses and local police said the Americans were ambushed after a meeting with Iraqi municipal officials.

The troops were hit by small-arms fire near Madain, an area with a volatile mix of Sunni and Shiite extremists about 15 miles southeast of Baghdad. A suspected militant also was killed, said Maj. John Hall, a U.S. military spokesman.

The soldier’s death Monday raised to at least 4,103 the number of members of the U.S. military who have died in the Iraq war since it began in March 2003, according to an Associated Press count.