Kabul --

August has become the deadliest month yet for U.S. forces in the nearly 10-year-old war in Afghanistan, increasing pressure on the Obama administration to bring troops home sooner rather than later.

The 66 U.S. service members killed this month eclipses the previous record of 65 killed in July 2010, according to an Associated Press tally. Nearly half the August deaths occurred when insurgents shot down a Chinook helicopter Aug. 6, killing 30 American troops, mostly elite Navy SEALs.

Violence is being reported across Afghanistan despite the U.S.-led coalition's drive to rout insurgents from their strongholds in the south.

Though American military officials predicted high casualties this summer as the Taliban try to come back after recent offensives, the grim milestone increases pressure on the Obama administration to withdraw U.S. forces quickly.

The military has begun to implement President Obama's order to withdraw the 33,000 extra troops he dispatched to the war. He ordered 10,000 out this year and another 23,000 withdrawn by the summer of 2012, leaving about 68,000 U.S. troops on the ground. Although major combat units are not expected to start leaving until late fall, two National Guard regiments comprising about 1,000 soldiers started going home last month.

Afghan President Hamid Karzai has set the end of 2014 as the target date for Afghan police and soldiers to take the lead in protecting and defending the country, leaving international combat forces to go home or take on more support roles.