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

The U.S. military said 96 U.S. troops have died so far in October, the highest monthly total since October 2005, when the same number of American forces was killed. The highest monthly death toll prior to that came in Jan. 2005, when 107 U.S. troops were 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.

Polls show a majority of Americans are opposed to Bush's handling of Iraq, and at a news conference in Washington on Wednesday, Bush 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."

Fighting continued today 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 U.S. coalition forces and their Iraqi allies.

At least five policemen were killed and 10 injured 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, police spokesmen said.

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 on Wednesday in Anbar province, a hotbed of the Sunni insurgency.

Names were being withheld pending notification of their families.

U.S. officials have said October's higher death toll is linked to a historical spike in violence during the Muslim holy month of Ramadan, which ended this week, as well as additional patrols launched as part of a security drive in Baghdad.

The deadliest month for U.S. forces since the March 2003 invasion came in Nov. 2004, when 137 troops were killed in an offensive against the insurgent stronghold of Falujah.