The U.S. military in Iraq says two Marines and one sailor were killed during combat operations against enemy forces.
A military statement issued Friday said the clash occurred Thursday in western Iraq's Anbar province.
The military also said that it has arrested two people suspected of attacking U.S. forces Wednesday in Baghdad.
After months of declining violence across the country, violence has surged in recent weeks. More than 50 people were killed in bombings in and around Baghdad Wednesday and, last week, explosions claimed the lives of more than 150 people.
U.S. Secretary of Defense Robert Gates Thursday blamed the surge of attacks on al-Qaida. Gates said it is "an orchestrated effort" by the group "to provoke the kind of sectarian violence that tore the country apart in 2006."
Gates said the bombers are trying to take advantage of the draw-down of U.S. forces in Iraq. Troops are set to withdraw from Iraqi cities in June, and leave the country next year.
During testimony on Capitol Hill, he downplayed the importance of Iraqi Prime Minister Nouri al-Maliki's efforts to reach out to Sunni groups, which critics say have been insufficient.