A leading U.S. newspaper says the senior commander for U.S. special forces in Afghanistan has suspended training for all new Afghan recruits until all Afghan troops can be re-investigated for ties to the insurgency.

The Washington Post reported Saturday the re-vetting process for the more than 27,000 Afghan troops working with the special forces comes as NATO officials struggle to stop the wave of attacks on NATO service members by their Afghan colleagues.

The newspaper says the killing of 45 troops this year has forced NATO officials to acknowledge what the Post says is a “painful truth” — that the killings might have been prevented if existing security measures had been applied correctly.

The report says many military guidelines, according to NATO officials, were not adhered to by Afghans and Americans because they did not want to hinder the growth of the Afghan army and police.

Special Operations officials say the current vetting process is effective, but lacks a follow-up that would screen out Afghan troops who have fallen under the influence of the insurgency or who have grown disillusioned with the Afghan government.

The Washington Post reports NATO officials say they knew that in some instances the vetting process for Afghan soldiers and police was never properly implemented. The officials said they overlooked it because they were concerned that the extensive background checks would slow down the recruitment process.