In late 2012 the Afghan campaign by NATO and the U.S. came to a screeching halt for several weeks. Advisors were told to not meet with their Afghan counterparts; partnered units were instructed to stick to unilateral operations, and combat operations were dramatically down-scaled. The cause of this drastic reduction in operations was the significant increase in 'green-on-blue attacks' - later referred to by ISAF as 'insider attacks'. Afghan policemen and soldiers were killing Coalition Servicemen at an increased rate. The increased rate of attacks, if not stemmed, would have a strategic effect. Defense ministers of European countries were calling General John Allen (ISAF cdr) and threatening the withdrawal of their forces if Afghan security personnel continued to kill their soldiers. Eventually a series of steps - Guardian Angels, vetting of Afghan security personnel, cultural awareness classes, situational awareness instruction, force protection measures, etc. - slowed down the rate of insider attack incidents. These measures, once implemented, allowed the Coalition Forces to resume their partnered and security force assistance missions.
This insider threat continues to exist today. The advisors of the many countries working with their Afghan counterparts continue to keep force protection as an integral part of their operational planning and execution. In the Spring of 2018 the 1st SFAB will deploy 36 advisor teams to Afghanistan to work at the tactical level with the Afghan National Defense and Security Forces (ANDSF). Presumably the advisors are well-trained in force protection measures and have an appreciation of the insider threat.
More Info on Insider Threats
Read the account of one insider attack that took place in Helmand province in August 2012 in "Why Some Marines Fear Afghan Allies More Than the Taliban", by James Laporta and Rory Laverty, The Daily Beast, February 6, 2018.
Description and Info about the Insider Threat from the ANDSF
News Reports about the Insider Threat from the ANDSF
Afghan War Blog - Posts about Insider Attacks and Threats
Afghan War Blog - Posts about Green-on-Blue Attacks
Statement by General Dunford, ISAF Commander - April 20, 2013 on Insider Threats
Insider Threat References
ISAF Insider Threat Handguide 2.0, June 2014