CAIRO (AP) — Militants from the Islamic State group attacked military barracks in central Syria this week, killing nine soldiers, an opposition war monitor said. The Syrian army and officials have not confirmed the attack.

IS claimed responsibility for the attack on Monday near the town of Al-Sukhna, saying its fighters also seized weapons abandoned by fleeing soldiers and set fire to the barracks. The militants’ statement claiming responsibility was posted late on Tuesday.

The attack was the latest in intensifying clashes in the desert in eastern Syria between the militants and the Syrian army, supported by Iran-backed militias.

The Britain-based Syrian Observatory for Human Rights, a war monitoring group, says IS has carried out 41 attacks so far this year there.

The Observatory said three Syrian troops were wounded in addition to the nine killed in Al-Sukhna.

IS militants have found refuge in the desert in remote areas in Syria and along the Iraqi-Syrian border, where they continue to stage attacks nearly five years after the group was defeated in Syria in 2019.

U.S. troops in northeastern Syria and U.S.-backed Kurdish-led Syrian Democratic Forces have conducted numerous operations against the remaining IS militants. The United States has approximately 900 troops in Syria focused on countering the group’s remnants.

Since war erupted in Gaza on Oct. 7 following Hamas’ surprise attack and incursion into southern Israel, U.S. bases in eastern Syria and Iraq have come under regular attack by an umbrella group of Iran-backed Iraqi militias called the Iraqi Islamic Resistance.

The militias say the attacks are in response to Washington’s support for Israel.