So how's that surge working for ya, George?

Not so well, it appears:

U.S. forces had one of their costliest days in Iraq on Saturday when 21 troops were killed, including 13 in a helicopter and five in a clash in a Shi'ite holy city the U.S. military said was triggered by militiamen.

The battle at a government building in Kerbala was the bloodiest for U.S. troops in the Shi'ite south in two years and occurred as President George W. Bush presses leaders of the Shi'ite majority to crack down on militias from their community.

Hours after reporting three deaths in separate incidents and the loss of all 13 passengers and crew aboard a Blackhawk transport helicopter, the U.S. military said five soldiers were killed and three wounded in the Kerbala clash.

It was the deadliest day for U.S. forces since Bush announced 10 days ago he was sending about 20,000 troops to Iraq to try to prevent sectarian civil war between Shi'ites and the once- dominant Sunni Arab minority. His plans have run into resistance from opposition Democrats who now control Congress.

It was unclear whether the helicopter was shot down. Residents in violent Diyala province northeast of Baghdad said they saw a helicopter in flames in the air.