KABUL, Afghanistan, Jan. 10 (UPI) -- The number of casualties from improvised explosive devices in Afghanistan has nearly quadrupled since U.S. President Obama took office, officials said.
Additionally, roadside bombs caused more U.S. troop casualties in 2010 than in the prior eight years of the war, USA Today reported.
Since the war began nine years ago, 617 American troops have been killed by IEDs and most of those deaths came in the past two years.
"It's clear that the insurgency in Afghanistan remains very robust," said John Nagl, a former Army officer and president of the Center for a New American Security, a Washington think tank. "As we increase our capabilities in the country and the region, they are also 'surging.'"
There are nearly 100,000 American troops in Afghanistan, up from about 30,000 two years ago, when Obama took office. They are joined by 50,000 international forces and are aided by more than 200,000 Afghan army troops and police.
The higher injury and death tolls are the result of troops moving into Taliban-held areas and forcing them to fight back, said the U.S.-led International Security Assistance Force that oversees the war effort.
A relatively mild winter has kept mountain passes open, allowing insurgents to travel more freely. The ISAF said al-Qaida is directing militants to return to areas they were forced out of by American and Afghan forces and fight back.