The Pentagon on Thursday admitted to accidentally killing 18 U.S.-backed Syrian fighters on Tuesday during a coalition operation against the Islamic State (ISIS).

"A coalition air strike in support of partnered forces fighting ISIS south of Tabqah, Syria, resulted in 18 Syrian Democratic Forces personnel killed April 11," reads the statement from U.S. Central Command (CENTCOM).

The strike, it continued, "was requested by the partnered forces, who had identified the target location as an ISIS fighting position. The target location was actually a forward Syrian Democratic Forces fighting position."

It was not clear if the strike came from a U.S. military plane or that of another coalition member.

"The U.S. is literally bombing everyone now," quipped journalist Asaad Hanna, a Syrian civil society and human rights activist, in response to the news. The so-called "friendly fire" incident occurred just days after U.S. President Donald Trump took unilateral military action and bombed a Syrian government airfield.

As the The Independent observed on Thursday, this week's killing of Syrian forces "is the latest in several recent U.S.-led strikes against ISIS and al-Qaeda in Syria and Iraq which have accidentally hit allied or civilian targets," coming mere weeks after U.S. military airstrikes killed more than 200 civilians in Mosul, Iraq.

According to CENTCOM, the U.S.-led coalition is assessing the cause of Tuesday's incident and "will implement appropriate safeguards to prevent similar incidents in the future."