(Massoud Hossaini/AP Photo)

Afghan security forces continued this year to sustain high rates of casualties with the top U.S. commander in Afghanistan estimating that as many as 7,000 to 9,000 Afghan security forces were killed or injured in combat. The increase in casualties began last year when Afghan security forces took the lead for security throughout the country.

Gen. John Campbell, the top US and ISAF commander in Afghanistan, told reporters Thursday he did not have the precise numbers but estimated that the overall number of Afghan casualties (killed and wounded) was "in the neighborhood of 7,000 to 9,000 for '14."

For comparison since the arrival of U.S. military forces in Afghanistan in October, 2001 there have been 2,208 American fatalities and almost 20,000 injured.

There are 352,000 Army and police personnel in Afghanistan and Campbell said the highest numbers of casualties are among Afghan police. "There's much greater percentage rate on the police because that's really the first line of defense. The police are not trained. They're not equipped the same level that the Afghan army and the special operating forces are equipped. So they've probably taken the brunt of those casualties."

Campbell acknowledged that the casualty numbers were "slightly higher" than last year during the summer fighting months. He said that in the last month the numbers have "gone up to kind of get it to where it was in '13. But that's because they've been in the lead almost completely this summer, more so than they were last year."

In January, then-Lt. General Mark Milley, who commanded operations in Afghanistan at the time said that casualty rates had increased significantly in the 2013 summer fighting season.

"Their casualties increased depending on the unit anywhere between 50 percent and 70 percent," said Milley.

But the general said they remained an effective fighting force as they held their ground during Taliban offensives. "I can tell you that there was probably somewhere in the range of 3,000 to 4,000 firefights in this past fighting season, if you will. And of those, several thousands of firefights the Afghan security forces probably lost somewhere between 100 and 150 maybe," said Milley.

There are currently 26,000 US troops in Afghanistan and with the newly-signed Bilateral Security Agreement Campbell said that will fall to 9,800 troops will be reached by the end of December. He indicated it was actually ahead of schedule and that the troop goal might be reached by November 1.

There will be almost 3,000 troops from other NATO countries that will remain in Afghanistan past this year for the operation that will be called "Resolute Support."

Campbell said that Resolute Support will work to make up for capabilities the Afghan security forces will still need. "We'll work very hard on their aviation, on their intelligence, on their sustainment, those things that are very, very hard for any army, especially hard here in Afghanistan," said Campbell.

In the meantime he expressed confidence that Afghan forces "have the capability to withstand the fight internally inside here in Afghanistan. They're very confident as well."

The advise and assist mission will continue at the Afghan Corps level and Campbell called the advisers "our new weapon system." He explained, "those are the folks that will be out there, engaged at the right levels to really work on the gaps and seams that we identified probably a year and a half ago with our Afghan partners here."