KABUL, Afghanistan (AP) — NATO’s decision to restrict operations with small Afghan forces to mitigate the threat of insider attacks means fewer boots on patrols and a shift in how the U.S.-led coalition will fight the war in Afghanistan.

It’s unclear whether the coalition’s exit strategy can succeed with less partnering with Afghan policemen and soldiers, who are slated to take over for foreign combat troops by the end of 2014, just 27 months from now. What is clear is that the mantra that Afghans and coalition forces are fighting the Taliban ‘‘shoulder to shoulder’’ is looking more and more like they’re standing at arm’s length.

Earlier this year, the U.S. military stopped training about 1,000 members of the Afghan Local Police, a controversial network of village-defense units. U.S. commanders have assigned some troops to be ‘‘guardian angels’’ who watch over their comrades in interactions with Afghan forces and even as they sleep. U.S. officials also recently ordered American troops to carry loaded weapons at all times in Afghanistan, even when they are on their bases.

Until now, coalition troops routinely conducted operations such as patrolling or manning outposts with small units of their Afghan counterparts. Under the new rules issued on Sunday, such operations with small-sized units are considered no longer routine and require the approval of the regional commander.

NATO’s decision reflected escalating worries about the insider attacks, coupled with the widespread tensions over an anti-Islam video that has prompted protests around the world, including Afghanistan.

Early Tuesday, a suicide bomber rammed a car packed with explosives into a minibus carrying foreign aviation workers to the airport in the Afghan capital, killing at least 12 people including nine foreigners — eight South Africans, a Kyrgyzstani and three Afghans.

Haroon Zarghoon, a spokesman for the Islamist militant group Hizb-i-Islami, claimed responsibility, saying it was carried out by a 22-year-old woman named Fatima and was meant to avenge the anti-Islam film that ridicules the Prophet Muhammad.

But the underlying reason for the new directive that curbs contact between Afghan and international forces is the spike in insider attacks.

So far this year, 51 international service members have died at the hands of Afghan forces or militants wearing their uniforms. That is more than 18 percent of the 279 international troops who have been killed in Afghanistan since the beginning of the year, according to figures compiled by The Associated Press.

U.S. Defense Secretary Leon Panetta argued that the attacks do not mean the Taliban are getting stronger. ‘‘I think what it indicates is that they are resorting to efforts that try to strike at our forces, try to create chaos but do not in any way result in their regaining territory that has been lost,’’ he told reporters during a press conference in Beijing.

Still, critics pointed out that insider attacks — which have continued despite efforts to vet all 352,000 members of Afghanistan’s army and police forces — were undermining the international mission in Afghanistan.

In London, lawmakers criticized the new restrictions on partnered operations as potentially undermining the strategy of training local forces to provide security once U.S. and NATO forces leave Afghanistan at the end of 2014.

‘‘It does appear to be a really significant change in the relationship between (coalition) and Afghan forces,’’ said opposition Labour Party lawmaker Jim Murphy.

British Defense Secretary Philip Hammond told lawmakers that troops would ‘‘return to normal operations’’ as soon as the tension eased.

The coalition also downplayed the impact of the directive, saying international forces had not stopped partnering and advising Afghan forces. Coalition officials said the new restrictions were made at the recommendation of — and in conjunction with —key Afghan leaders.

Companies remain partnered with Afghan units, but have changed the way they conduct their daily partnering operations with units smaller than a battalion, according to the coalition.

Battalions — or kandaks as they are called in Afghanistan — differ in size, but typically have about 300 to 500 service members. In Afghanistan, however, most of the fighting occurs with tens not hundreds of troops.