KABUL, Afghanistan (AP) — The U.S. military has suspended training of some Afghan forces while the Americans review the process of vetting new recruits following a spike in deadly attacks on international troops last month, officials said Sunday.

There have been 34 attacks by Afghan police or soldiers on their international allies so far this year — at least 12 in August alone. The members of the Afghan security forces have killed 45 international troops, putting intense strain on the relationship. The attacks have complicated a key pillar in the plan for the U.S.-led coalition to withdraw by the end of 2014 — training Afghan forces to take the lead in securing their own country.

Lt. Col. Todd Harrell, a spokesman for U.S. special operations forces in Afghanistan, said the Americans have halted training for at least a month of about 1,000 trainees of the Afghan Local Police (ALP), a government-backed militia that is under the authority of the national police but operates independently. He said the Americans are redoing background checks on the Afghans.