In a report released Friday by the U.S. Defense Department, the Pentagon said the security situation in Afghanistan has been markedly improved this year but said militants operating from safe havens in Pakistan pose significant risks to a “durable, stable Afghanistan.”

The department said violence declined particularly in Afghanistan's southwest, west and north.

But security in the country's eastern region remains tenuous because of “the sanctuary and support” the insurgents receive from Pakistan.

The report comes as President Barack Obama's administration has begun pulling so-called “surge” forces from Afghanistan — withdrawing 10,000 this year and the remaining 23,000 by the end of September 2012.

The Pentagon said despite the recent high-profile attacks in Kabul, overall enemy attacks were five percent lower than the same period a year earlier.

The report said the security gains provide a firm foundation for gradually putting Afghan forces in charge of security, a goal now set for the end of 2014.