The United Nations on Tuesday condemned the Syrian military’s breach of the demilitarized zone between the Israeli and Syrian Golan Heights on Saturday, calling it a violation of the 1974 disengagement agreement .

UN Spokesman Martin Nesirky said that the entering of the territory by three Syrian tanks could endanger the stability of the entire region.

The UN Undersecretary for Political Affairs Jeffrey Feltman also warned of a deterioration of stability along the Israeli-Syrian frontier. He said the spillover of Syrian violence into the Golan Heights, as well as into Turkey and Lebanon, “raised concerns about a regional explosion,” Israel Radio reported.

The crossing into the DMZ (Demilitarized Zone) by Syrian armor on Saturday was the first such violation in 40 years. The Syrian army vehicles were deployed just a few miles away from Israeli military positions. Several mortar shells from the Syrian fighting had reportedly fallen in the same area in recent days, and one of them may have caused a small fire.

Israel promptly filed a complaint with the UN peacekeeping force in the area, and the IDF raised its alert level.

Ron Prosor, Israel’s ambassador to the UN, also sent a letter of complaint to the UN Security Council in which he claimed the tanks were still in the DMZ. He stated that Israel had exhibited great levels of restraint thus far, but that it was concerned that the Syrian civil war could spill over into Israel — and that it could have far-reaching implications for security in the region.

The DMZ, which is about 7 kilometers (3.5 miles) at its widest and 200 meters (yards) at its narrowest, was created after the 1973 war in which Syria tried to retake the strategic plateau.

Israel captured the Golan Heights from Syria in the 1967 Six Day War and the shared border has been largely quiet since 1974.

Also on Tuesday, the Israeli military said that a stray bullet from fighting in nearby Syria set off a land mine in the Golan Heights, sparking a fire.

The military said firefighters extinguished the blaze. It was believed to have been set off by misdirected gunfire from Syria. Yoram Levy, a spokesman for the fire and rescue service, said a small fire burned on a minefield. Some parts of the Golan are still littered with land mines.

The shot into Israel comes a day after an Israeli army jeep was hit by by stray gunfire from Syria Monday evening. Several bullets, evidently fired during clashes between rebels and government forces on the other side of the Syrian frontier, hit and lightly damaged an IDF vehicle. No injuries were reported.

The army dispatched soldiers to the area and was investigating the scene of the incident, an IDF statement said. It also lodged a complaint with the UN peacekeeping force.

Aaron Kalman contributed to this report.