11 June, 2017
This intensified push against ISIS comes as the Taliban also steps up its activity targeting USA and Afghan forces elsewhere in the country. This incident is under investigation.
"A Mujahid (freedom fighter) infiltrator of the Islamic Emirate who had enrolled himself in the Kabul government's army attacked American soldiers in Lata Band area of Achin district in Nangarhar province today in the afternoon", said a written statement in Pashto obtained by CNN.
One American official said the soldiers were shot in an apparent insider attack, also known as a "green-on-blue" because of the color-coding system used by North Atlantic Treaty Organisation.
A White House spokesperson traveling with Donald Trump in New Jeresey said the U.S. president was aware of and following the situation. They say a number of militants were also killed in the strike.
The US military has not yet released a statement on the incident.
Afghan officials initially reported that two USA service members were killed, but US officials later said three died.
USA and Afghan forces however have been battling Islamic State militants in Nangarhar province since the beginning of 2015. While Afghan officials said dozens of militants were killed, the Pentagon has remained mum on what exactly the bomb accomplished.
Two Afghan border policemen were also recently killed by USA aircraft friendly fire during a joint operation in the southern province of Helmand.
In April, the United States military dropped its largest non-nuclear bomb ever used in combat on a complex of caves in Achin used by IS fighters.
So-called green-on-blue attacks - when Afghan soldiers or police turn their guns on worldwide troops - have been a major problem during NATO's long years fighting alongside Afghan forces.
Earlier this year, the top US intelligence official said the security situation in Afghanistan will further deteriorate even if there is a modest increase in USA military support for Afghanistan. Around 2,000 of them are involved in counterterrorism operations. The attacker was killed after USA troops returned fire.
In recent months, the Taliban have captured several districts in Helmand and put provincial capital Lashkar Gah under pressure.
United States troops in Afghanistan number about 8,400 today, and there are another 5,000 from North Atlantic Treaty Organisation allies.