A group of about 300 Islamic State (IS) fighters halted by US airstrikes on Wednesday after retreating from the Lebanese border is heading back into the heart of territory controlled by President Bashar al-Assad of Syria, US military officials said today.

The militants were released by the Lebanese Shiite militia Hezbollah on Tuesday in exchange for the bodies of Lebanese soldiers and Hezbollah fighters captured by the group. They had been traveling toward the IS-controlled Deir ez-Zor province, where they had hoped to link up with IS fighters in Iraq. The US-led coalition fighting the group in Syria interrupted those plans Wednesday, cratering the road toward the battlefront with airstrikes.

“They actually started moving back toward the interior of Syria, and so we're just letting them go,” Lt. Gen. Stephen Townsend, who commands the US-led coalition in Iraq and Syria, told reporters at the Pentagon via video link from Baghdad. “If they try to get to the edge of [IS] territory and link up with [IS] there, we'll work hard to disrupt that.”

It’s not clear that the strikes will impact the Pentagon’s long-standing military-to-military relationship with the Lebanese Armed Forces, including the recent delivery of eight M2A2 Bradley Fighting Vehicles. As Lebanon has dealt with increased attacks from IS, the United States has bolstered weapons sales to its army, selling it six A-29 Super Tucano aircraft (which are designed for close support and counterinsurgency missions) as well as six Huey helicopters.