US forces in Syria have begun airdropping troops behind ISIS lines near the town of al-Tabqa, and near the important Tabqa Dam. The exact details of the airdrop are still emerging but they are said to include some US Marines as well as a number of Kurdish forces.

The area around Tabqa is just the latest in a series of targets for the Kurdish YPG as they attempt to surround the ISIS capital of Raqqa. Tabqa is about 25 miles west of the capital, and Kurdish YPG forces mostly control the area north of the city, though they’ve also made some efforts to take the northeast.

The US launched multiple airstrikes against the surrounding area to provide cover for the airdrop, which included an airstrike which hit a local school sheltering displaced civilians. The attack killed at least 33 civilians, with some reports suggesting the toll could rise further.

The airdrops, which began on Tuesday, were the first US airdrops of Kurdish forces so far in Syria, and the deployment of US Marines with them points to the continued escalation of direct US military involvement on the ground by the Trump Administration.

In recent weeks, the US has also deployed hundreds of other US Marines with howitzers into the area north of Raqqa, aiming to provide support for advances toward the city. While the Pentagon officially labeled the howitzer Marines “advisers,” there appears to be little doubt that they, along with the new airdropped troops, will be involved in combat in the course of this deployment.