KABUL — Afghan officials say they have launched an expanded effort to spy on their own police and army recruits, an acknowledgment that previous measures designed to reduce insurgent infiltration in the country’s security services have failed.

The steps come amid a spate of “insider” attacks that have shaken the U.S.-Afghan military partnership during a stage of the war that hinges on close partnership between the two forces.

Nine U.S. troops have been killed by their Afghan counterparts in the past 12 days. They are among 40 coalition service members who have died in insider attacks this year. President Obama, in his most extensive comments to date on the issue, said Monday that his administration is “deeply concerned about this, from top to bottom.”

The Afghan measures include the deployment of dozens of undercover intelligence officers to Afghan security units nationwide, increased surveillance of phone calls between Afghan troops and their families, and a ban on cellphone use among new recruits to give them fewer opportunities to contact members of the insurgency, Afghan officials say.

The initiatives appear aimed at addressing U.S. criticism that the Afghan security forces are not doing enough to ferret out insurgents within their ranks. The top U.S. military official, Gen. Martin Dempsey, was in Kabul on Monday for consultations on the matter, and Obama said he would soon be “reaching out” to Afghan President Hamid Karzai.

“Soldiers must feel that they are under the full surveillance of their leadership at all levels,” the Afghan army chief of staff, Gen. Sher Mohammad Karimi, said in an interview after meeting with Dempsey and other U.S. commanders. “Initially, it will have a negative impact on morale, but we have to do something. We have to look seriously at every individual.”

Coalition policy changes

NATO has taken steps in recent days to try to limit the attacks, which Taliban leader Mohammad Omar has described as an integral part of his group’s strategy.

Across Afghanistan, service members have been asked to keep their weapons loaded at all times, according to coalition officials. NATO has also activated an existing program, dubbed “Guardian Angels,” in which coalition troops whose only job is to watch their fellow troops attend meetings with Afghan officials prepared to quell an insider attack if one should occur.

Obama said U.S. forces are “seeing some success when it comes to better counterintelligence, making sure that the vetting process for Afghan troops is stronger.” But, he added, “obviously, we’re going to have to do more, because there has been an uptick over the last 12 months on this.”

Insider attacks are a relatively new aspect of the war, having emerged as a major problem for the United States and its allies only in the past several years. There have been more deaths from insider attacks in 2012 than in any other year of the war, and they have accounted for 13 percent of all NATO fatalities this year.

Tight choreography

As U.S. troops begin to withdraw, the attacks threaten to upend plans for a transition from foreign to Afghan control of security that will require tight choreography between the two forces.