BAGHDAD, Iraq (AP) - Five bicycle bombs and a hail of mortar shells ripped apart a market south of Baghdad, killing 18 people in yet another sign that Iraq’s government and U.S. forces were struggling to contain sectarian violence. Three U.S. Marines also were killed, making October the deadliest month for American forces this year.

In Washington, President George W. Bush met with his top military and security advisers Saturday to study new tactics to curb the staggering violence in Iraq, where more than 3 1/2 years of war have now taken more American lives - at least 2,791 - than the Sept. 11 attack on the World Trade Center.

U.S. officials have blamed the skyrocketing violence on the holy month of Ramadan, which ends Sunday for Sunni Muslims, as well as the increased vulnerability of American forces during a major two-month security sweep in Baghdad and the approaching U.S. midterm election.

A senior U.S. State Department official offered an unusually candid assessment of the security situation in an interview Saturday with Al-Jazeera television, saying the U.S. had shown "arrogance" and "stupidity" in Iraq. Alberto Fernandez, director of public diplomacy in the Bureau of Near Eastern Affairs, also said the U.S. was ready to talk with any Iraqi group except al-Qaida in Iraq to facilitate national reconciliation.