A Russian airstrike that was intended for Islamic State militants in Northern Syria mistakenly bombed a coalition of Syrian and Arab troops being trained by the United States, Army Lt. Gen. Stephen Townsend told reporters Wednesday.

American military advisors tasked with training and advising the Syrian Democratic Forces were less than three miles away from the location where the joint Russian and Syrian attack occurred Tuesday, said Townsend, who heads U.S. forces in the fight against the Islamic State in Syria and Iraq. The incident, which took place in a town just outside of Raqqa, which has become the Islamic extremist group’s de facto capital in Syria, resulted in casualties among members of the Syrian Democratic Forces, but Townsend declined to comment on how many were injured or if there were any deaths.

“We had some Russian aircraft and [Syrian] regime aircraft bomb some villages that I believe they thought were held by ISIS, " Townsend told reporters in a Pentagon news briefing Wednesday. “Actually on the ground were some of our Syrian Arab coalition forces.”

Despite Townsend’s comments, Russia’s Defense Ministry denied both its and the Syrian military's involvement in the bombings, saying "not a single airstrike" was performed by either country, Russian government-funded outlet RT reported Wednesday.

The incident painted a grim picture of the crowded Syrian battlefields surrounding Raqqa, as Townsend said troops representing allied countries like Turkey were oftentimes, “within hand-grenade range of one another.”

A similar incident had occurred on Feb. 9, 2016, when a Russian airstrike, that the country claimed was an accident, killed three Turkish soldiers in the northern town of Al-Bab after Turkey’s army allegedly provided them with the wrong coordinates about their troops' location, Russian news outlet Sputnik International reported Feb. 10, 2016.

The U.S. and Russia created a hotline in 2015 between an American colonel in Qatar and a Russian colonel in Syria to prevent aerial collisions from occurring, but senior U.S. defense officials have not communicated directly with their Russian counterparts since 2014 due to legislation forbidding military cooperation with Russia in response to its annexation of the Crimea, the Washington Post reported Wednesday.

The two countries were seemingly on opposing sides of the Syrian Civil War, with the Kremlin hoping that Syrian President Bashar Assad remains in power and the U.S. viewing his removal as essential towards achieving peace in the conflict that has killed an estimated 400,000 people since starting in March 2011. However, Townsend said the U.S. military wouldn’t be deterred by the Russian airstrike, but rather remain focused on continuing to fight alongside Russia against Islamic State militants in Syria.