BAGHDAD, Iraq - The number of American troops killed in Iraq in October reached the highest monthly total in a year Thursday after four Marines and a sailor died of wounds suffered while fighting in the same Sunni insurgent stronghold.

The US military said 96 US troops have died so far in October, the most in one month since October 2005, when the same number was killed. The spike in deaths has been a major factor behind rising anti-war sentiment in the United States, fueling calls for President Bush to change tactics.

In other violence, 12 police officers were killed in fighting with suspected militia gunmen in Baqouba, northeast of Baghdad, officials said. Eighteen militants also were killed.

The deadliest month for US forces in Iraq was November 2004, when military offenses primarily in the then-insurgent stronghold of Fallujah, 40 miles west of Baghdad, left 137 troops dead, 126 of them in combat. In January 2005, 107 US troops were killed.

Polls show a majority of Americans are opposed to Bush's handling of Iraq, and at a news conference in Washington on Wednesday, he indicated he shared the public's frustration even as he pushed back against calls for troop withdrawals.

"I know many Americans are not satisfied with the situation in Iraq," Bush said. "I'm not satisfied either."

Gen. William B. Caldwell, the US military spokesman, said there had been a marked decrease in violence in Baghdad since the end of Ramadan, the Muslim month of fasting, earlier this week.

Caldwell said violence has in the past tended to spike during that month, then fall off. He also said it was possible increased U.S. patrols and roadblocks in the search of a missing American soldier could be having an effect.

"Everyone is asking this very same question ... whether this is occurring naturally or is it due to the fact that we in fact established and are conducting these additional operations," he said.

Defense Secretary Donald H. Rumsfeld said the United States would increase its support for Iraqi security forces.

"We intend to increase their budgets," he said, as well as their capabilities, and officials will work to help make the improvements more quickly. He did not cite any figures.

Rumsfeld also said people ought to "just back off" and stop demanding specific benchmarks or timelines for progress in Iraq, saying it is just too difficult to predict when the Iraqis can take control of security.

Fighting continued Thursday with fresh clashes between Iraqi security forces and militia groups linked to major Shiite political parties, part of an ominous new trend adding to the violence wrought by the Sunni-led insurgency against US coalition forces and their Iraqi allies.

At least 12 policemen were killed in fighting near Baqouba pitting Iraqi security forces against gunmen of the Mahdi Army militia, who are loyal to fiery anti-American Shiite cleric Muqtada al-Sadr. At least 18 militants also were killed, said Ghassan al-Bawi, police chief of surrounding Diyala province.

Mahdi militiamen have flooded into the area 35 miles northeast of Baghdad, forcing large numbers of residents belonging to Iraq's Sunni Arab minority to flee their homes. Mahdi fighters killed scores of Sunnis in massacres last week in the nearby city of Balad, forcing U.S. troops to return to the area after Iraqi security forces were unable to stem the bloodshed.

The U.S. military said the five service members killed in volatile Anbar province included a sailor assigned to the 3rd Naval Construction Regiment. Two of the Marines were attached to Regimental Combat Team 5, and two others to Regimental Combat Team 7. All died from wounds suffered in attacks Wednesday in Anbar province, a hotbed of the Sunni insurgency.

According to Gen. George Casey, the top US commander in Iraq, about 300 Iraqi police and soldiers died during Ramadan, while altogether, more than 961 Iraqis have been killed in war-related violence this month, the highest level since The Associated Press began tracking civilian deaths in April 2005.

That amounts to an average of more than 41 each day, compared with a daily average of about 27 since April 2005, as more Iraqis fall prey to sectarian death squads affiliated with the militias.

The AP count includes civilians, government officials and police and security forces, and is considered a minimum based on AP reporting. The actual number is likely higher, as many killings go unreported. The United Nations has said 100 Iraqis are being killed each day.