"The militants were observed loading weapons in to a vehicle and were under surveillance until the vehicle was destroyed by an airstrike", said Bob Purtiman, a spokesman for American operations in Afghanistan.
The attack on August 10 killed Abdul Rahman, identified by the USA military as the Kunar Provine emir for Islamic State of Iraq and Syria-Khorasan (ISIS-K), according to a statement from the command in Kabul. "There was zero chance of civilian casualties".
Dawlat Waziri, a spokesman for Afghanistan's Ministry of Defense, said Thursday's strike was carried out by foreign forces in coordination with Afghan officials.
This is the second strike in the last few weeks in the district which killed civilians.
The United States now has about 8,400 soldiers in Afghanistan with another 5,000 troops from North Atlantic Treaty Organisation allies.
Last August، a USA drone attack killed 22 Afghan soldiers in Helmand، and in September that year airstrikes conducted by American warplanes claimed the lives of at least eight Afghan troops in the central province of Uruzgan.
USA forces have made it a goal to defeat ISIS-K in Afghanistan this year.
Last month a U.S. air strike killed 16 policemen in Helmand province. "But, we have appointed a delegation to investigate if civilians are killed".
Afghanistan is still suffering from insecurity and violence years after the United States and its allies invaded the country as part of Washington's so-called war on terror.
The war in Afghanistan is the longest in U.S. history with a cost of about $1 trillion.
US President Donald Trump has been skeptical about the military campaign in Afghanistan. "We do not have any news about civilian casualties".