President Barack Obama and Vice President Joe Biden at Fort Campbell, Ky., in May 2011. (AP Photo/Mark Humphrey)

(CNSNews.com) - Although President Obama has only served 39 months in office, 69 percent of the U.S. military fatalities in the more than 10-year-old war in Afghanistan have occurred on his watch.

Through April 30, the Defense Department had reported that 1,844 U.S. military personnel have been killed in and around Afghanistan while deployed in Operation Enduring Freedom, which was launched in October 2001 after al Qaeda terrorists attacked the World Trade Towers and the Pentagon.

According to CNSNews.com’s comprehensive database on Afghan war casualties, at least 1,275 of the 1,844 U.S. troops killed in the Afghanistan conflict have been killed since Jan. 20, 2009, when Barack Obama was inaugurated as president.

In the more than 10 years the U.S. military has been fighting in Afghanistan, each of the three deadliest years have been during Obama’s presidency. The deadliest year was 2010, when 497 U.S. service personnel gave their lives in Afghanistan. The second deadliest year was 2011, when 399 U.S. service personnel gave their lives in Afghanistan. And the third deadliest year was 2009, when 303 U.S. service personnel gave their lives in Afghanistan.

In recent years, some U.S. casualties in Afghanistan have come at the hands of the Afghan forces that the U.S. military is seeking to train so that they can defend their own country. Since 2007, when the Pentagon began tracking these killings, 54 U.S. soldiers have been killed by Afghan troops.

On March 22, Gen. John Allen, the top commander in Afghanistan, testified in Congress that as of that point 52 U.S. service personnel in Afghanistan had been killed by Afghan forces. Of those 52, Gen. Allen said, six had taken place this year alone.

Since Gen. Allen’s testimony, two more U.S. casualties at the hands of Afghan forces have come to light.

On March 16, the Associated Press reported that the Pentagon failed to identify a U.S. soldier killed by Afghan forces in February. On May 1, the Associated Press reported that on April 25 a U.S. Army special forces soldier had been killed by Afghan forces.

CNSNews.com’s detailed count of U.S. military fatalities in Afghanistan is derived from official casualty reports issued by the Department of Defense (DOD), augmented by information taken from ISAF and media accounts. (To see chart alone, click here.)

Month-to-Month U.S. Casualties in Afghan War

The database includes all U.S. military personnel who died or were fatally injured in and around Afghanistan while supporting military efforts in Operation Enduring Freedom, which covers multiple countries.

Besides the 1,829 American soldiers who have reportedly died on Afghan soil as of the end of April, CNSNews.com’s total count of 1,844 U.S. fatalities in and around Afghanistan includes 12 U.S. troops who died in Pakistan and three who died in the Arabian Sea while supporting Operation Enduring Freedom.