Baghdad, Iraq ? A suicide car bomber struck in the main Shiite district of the capital Wednesday, killing at least nine people as the U.S. military said its troop buildup in Baghdad was nearly complete.

At least 85 Iraqis were killed or found dead nationwide, police reported. They included eight people who lost their lives when a roadside bomb destroyed their minibus about 20 miles south of Baghdad.

Also Wednesday, two U.S. soldiers were killed and two others were wounded when a bomb devastated their vehicle in southern Baghdad, the U.S. command said. Another soldier died in a blast in western Baghdad, the command said.

At least 3,354 members of the U.S. military have died since the Iraq war started in March 2003, according to an Associated Press count.

Persistent bombings threaten to undermine the 11-week U.S. effort to restore order in the capital, which was racked by a wave of Sunni-Shiite slaughter last year that plunged the country into civil conflict.

“The explosions show the incompetence of the security plan,” said Saif Abdul-Khaliq, 28, who owns a stationery shop near the Sadr City blast site. “We expected security from this plan, but the only thing we got was traffic jams and blasts.”

U.S. officials have insisted that it’s too early to judge the effectiveness of the security plan because all American forces will not be deployed in the streets until next month.

On Wednesday, the U.S. military announced that its buildup of forces was nearly complete with the arrival this week of the fourth of five brigades ordered to Baghdad by President Bush in January.

About 3,700 soldiers from the 4th Brigade of the 2nd Infantry Division, based in Fort Lewis, Washington, will be deployed in the Baghdad area and in northern Iraq, the military said.

When the fifth brigade arrives by next month, the U.S. command will have about 160,000 American troops in the country.

The violence occurred on the eve of an international conference in the Egyptian resort of Sharm el-Sheik in a bid to boost economic and diplomatic support for Iraq.

Secretary of State Condoleezza Rice acknowledged international resistance to new financial and political support for Iraq – particularly debt relief.

“The region has everything at stake here; Iraq’s neighbors have everything at stake here,” Rice told reporters traveling with her to a gathering that will include U.S. adversaries Iran and Syria.