WASHINGTON -- The Pentagon says Afghanistan's overall security has deteriorated dramatically during the second half of 2015, with militants staging more effective attacks and Afghan forces suffering more casualties.
The December 15 report from the Pentagon, prepared for the U.S. Congress, came as President Barack Obama's administration struggles to bolster Afghan security forces amid a rising number of assaults by Taliban fighters and rival Islamic State militants.
Obama had hoped to wind down the U.S. wars in Afghanistan and Iraq before his second term concludes at the start of 2017.
But, in a reflection of the worsening security environment there, Obama announced a halt to the withdrawal of U.S. forces from Afghanistan -- with 9,800 troops to remain in place through most of 2016 before troop numbers under the current schedule would drop to 5,500 by early 2017.
The Pentagon said Afghanistan's military and security forces have struggled in the face of more frequent, and better planned attacks by Taliban and allied militias.
And the report was focusing on developments before the latest, and perhaps boldest, Taliban attack since the collapse of the Taliban regime in late 2001.
After sundown on December 9, Taliban suicide attackers staged a bold raid on Kandahar Air Field -- the second largest military base in Afghanistan and the logistics center for all NATO and Afghan military operations in southern Afghanistan.
The Taliban fighters managed to get inside the sprawling military compound, killing more than 50 people in a battle that lasted longer than 24 hours.
The Pentagon report did reflect on cases like a battle in September when Taliban overran the northern city of Kunduz, the first time that the Taliban seized and held a major city since the U.S. invasion in 2001.
Afghan security forces retook the city a week later, with U.S. air support.
The Pentagon report -- titled Enhancing Security and Stability in Afghanistan -- said there had been a 27 percent increase in casualties from January 1 through November 15 compared to the same period in 2014.
The performance of Afghan security forces during "the entire fighting season and the last six months has been uneven and mixed," the report said.
It said insurgent forces were becoming better able to "find and exploit [Afghan forces'] vulnerabilities making the security situation still fragile in key areas and at risk of deterioration in other places."
The report also noted that Islamic State militants -- who have seized swaths of territory in Iraq and Syria -- have become active in Afghanistan.
General John Campbell, the commander of U.S. and NATO forces in Afghanistan, told The Associated Press on December 15 that a growing number of Afghan militants were declaring loyalty to the Islamic State.
He also said fighters were trying to establish a regional base in the eastern city of Jalalabad and "foreign fighters" from Syria and Iraq were joining them.
With reporting by AP and Reuters