According to an Army statement, the U.S. military launched an investigation into whether a U.S. service member was involved in an April attack on a small U.S.-based base in eastern Syria that left four soldiers wounded.

Monday’s announcement was made by the Air Force Office of Special Investigations and the Army Criminal Investigation Division.

“Army CID (Air Force OSI) are conducting a joint investigation into the incident. The Army CID stated that a possible suspect, a U.S. Servicemember, had been identified in a statement to NBC News.

These are only allegations. All suspects are presumed innocent, unless they are convicted by a court. While the investigation is ongoing, it may or not produce sufficient evidence to identify perpetrators and enough evidence to warrant a conviction in court.

There have been no charges. CNN first reported on the investigation.

Initial reports stated that two mortar or rocket rounds had struck Green Village in eastern Syria in April. The attack left four U.S. soldiers with minor injuries and possibly traumatic brain injuries.

Later, the military stated that the attack was not due to indirect fire but rather explosives were placed within the base.

Many rocket attacks have been claimed by Iranian-backed militias on bases in Syria and Iraq.

As part of its efforts to combat the Islamic State terrorist group, the U.S. has deployed several hundred troops to eastern Syria.