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US-Afghan military operations suspended after attacks

Afghan security forces turned their guns on U.S. and NATO troops, killing four American soldiers and two British troops. NBC's Richard Engel reports.

Most joint U.S.-Afghan military operations have been suspended following what authorities believe was an insider attack Sunday that left four American soldiers dead, officials told NBC News.

“We’re to the point now where we can’t trust these people,” a senior military official said. So far this year, 51 NATO troops have been killed in these so-called blue-on-green attacks. Sunday's attack came a day after two British soldiers were shot dead by an Afghan policeman, Reuters reported.

Four NATO soldiers killed in Afghan 'insider' attack

"It's had a major impact on our ability to conduct combat operations with them, and we're going to have to back off to a certain degree," the official said.

The suspensions of the joint operations are indefinite – according to one official, they “could last three days or three months.”

The escalating violence — including a NATO airstrike that killed eight Afghan women and girls gathering firewood — is straining the military partnership between Kabul and NATO as the U.S. begins to withdraw thousands of troops sent three years ago to rout the Taliban from southern strongholds.

Afghan President Hamid Karzai condemned the airstrike; the U.S.-led International Security Assistance Force later extended its regrets over those deaths.

The U.S. training mission and joint combat patrols are "critical" to the U.S. plan to withdraw all combat forces by as early as the middle of next year and almost all U.S. military from Afghanistan by the end of 2014.

In May, President Barack Obama announced that he and Karzai signed an agreement that would see the removal of 23,000 U.S. troops from Afghanistan by the summer's end.

“As our coalition agreed, by the end of 2014 the Afghans will be fully responsible for the security of their country," Obama said at the time. But the president was clear that the U.S. would stay engaged into the future.

The Associated Press contributed to this report.

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