Top U.S. commander, Gen. Martin Dempsey, in Afghanistan amid spike in "insider attacks"

(CBS News) KABUL - Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey spoke Monday with U.S. and Afghan officials in Kabul amid a spike in "insider attacks" which has seen Afghan forces claim the lives of 10 U.S. troops during the last two weeks alone.

Dempsey first met Gen. John Allen, commander of both the International Security Assistance Force (ISAF), and U.S. forces in the country, to discuss the progress of the military campaign, which is to begin winding down after more than 11 years.

"Our session today was an excellent dialogue about how to maintain momentum against the insurgents and ISAF's continuing support to building Afghan capacity," Gen. Allen said in a statement released after the meeting. "The campaign remains on track."

But Dempsey's surprise visit to Afghanistan comes just a day after the latest insider attack, this time by two Afghan police officers, left one U.S. service member dead and one wounded. One of the two attackers escaped.

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Tackling the recent spate of similar incidents will be a major topic of discussion for Dempsey's visit. There have been 32 confirmed insider attacks so far this year. At least 40 coalition forces have been killed in such incidents in 2012, including 26 Americans.

ISAF and U.S. commanders say it is still too soon determine the motives for the attacks, as investigations into the latest incidents continue.

Previously, military officials said only around 10 percent of the insider attacks were due to infiltration of the Afghan security forces by the Taliban or other militant groups, and the rest of the attacks were apparently the result of personal grievances and combat stress.

But the frequency of the latest killings suggests a more coordinated campaign. Taliban Mullah Omar claimed last week a deliberate effort to get insurgents into the rank and file of the Afghan armed forces.

There is no way to verify Omar's claim, but if these attacks are cases of infiltration - however alarming this may sound - it may be easier to deal with than the alternative, which is a dramatic increase in unpredictable outbursts of rage as a potential symptom of deteriorating relations between Afghan and international forces.

Infiltration could potentially be reduced by using stepped-up intelligence measures, some of which are already in place. The Pentagon announced just last week that it would be expanding counterintelligence staff in Afghanistan to try and mitigate the threat of infiltration, but officials have given no details on the new measures or staff being hired.

New recruits to the Afghan security forces have long been subjected to an eight-point vetting process - covering everything from biometrics to background checks. They also have to submit character references from local tribal elders.

Another method of trying to protect international troops, which has been in use for most of this year, is the use of "Guardian Angels," elected troops embedded in U.S. military units to monitor any suspicious behavior by Afghan forces working alongside their American counterparts.

More recently, the U.S. military has announced that its forces should carry loaded weapons at all times, even when on base, as a precaution against insider attacks.

The U.S. military is also asking the Afghan government to step up its own preventative measures. On Saturday, U.S. Defense Secretary Leon Panetta called Afghan President Hamid Karzai to encourage more vigorous vetting of Afghan recruits and for Afghan forces to work more on counterintelligence.

So far, however, none of these efforts have proved very effective at curtailing the insider attacks, which seem to be alarmingly easy to pull off.

With a little less than half of 2012 left to go, the overall death toll for Western forces from insider attacks this year already stands at 40, and the pace has increased dramatically in recent weeks. In 2011, the total death toll from insider attacks was 35.

Once he has concluded his meetings with other officials in Kabul, including Karzai later on Monday, Dempsey was due to preside over an awards ceremony for soldiers of the Combined Joint Task Force at Bagram Air Base before leaving Afghanistan later in the day.

CBSNews.com foreign editor Tucker Reals edited this story.