An abandoned United Nations Disengagement Observer Force (UNDOF) post in the no-man’s land between Syria and Israel in the Golan Heights was taken over by pro-Assad military forces, according to Israeli media on Sunday.

According to a cessation of hostilities agreement between Israel and Syria following the 1973 Yom Kippur War, no troops from either nation are allowed to occupy the space. However, UNDOF, which abandoned the position in 2014, has reported that it has detected ongoing infrastructure work at the post.

The Israel Defense Forces responded that the Syrian takeover of the post constitutes a “serious and flagrant violation of the separation-of-forces agreement,” and suggested that Israel’s military may take measures to empty enemy forces from the site by force.

Just hours prior to the release of the report, an Israeli Patriot missile was fired at a drone believe to belong to regime forces that approached Israeli airspace.

The incident is consistent with a serious uptick in tensions between Israel and Syria in the past months. Israel has launched several attacks on Iranian military apparatus embedded in Syria, and Syria has been the launching point of rockets and drones against Israel.

UNDOF was created in 1974 by the United Nations to oversee a peaceful border between Israel and Syria. Workers are deployed within and close to the zone with two base camps, 44 permanently manned positions and 11 observation posts.

The total budget for UNDOF for the period from July 1, 2017 to June 30, 2018 was $62,276,000.