Prime Minister Benjamin Netanyahu said on Tuesday Israeli forces will stay in a buffer zone on the Syrian border, and specifically on the summit of Mount Hermon, “until another arrangement is found that will ensure Israel’s security.”

Mr. Netanyahu made the comments on Tuesday from the mountain’s snow-dusted summit — the highest peak in the area — which is located on Syria’s side of the border. This was apparently the first time a sitting Israeli leader entered the Syrian territory.

Mr. Netanyahu said he had been on the summit of Mount Hermon 53 years ago as a soldier, but the summit’s importance to Israel’s security has only increased given recent events.

Israel seized a swath of southern Syria along the border with the Israeli-annexed Golan Heights, calling it a buffer zone, in the days after Syrian President Bashar Assad was ousted by rebels. Israel’s capture of the buffer zone has sparked condemnation, with critics accusing Israel of violating a 1974 ceasefire and possibly exploiting the chaos in Syria for a land grab.

Mr. Netanyau visited the buffer zone with Defense Minister Israel Katz, who said he instructed the Israeli military to quickly establish a presence including fortifications, in anticipation of what could be an extended stay in the area.

“The summit of the Hermon is the eyes of the state of Israel to identify our enemies who are nearby and far away,” Mr. Katz said.

Israeli forces moved to control a roughly 400-square-kilometer (155-square-mile) demilitarized buffer zone in Syrian territory. The buffer zone between Syria and the Israeli-controlled Golan Heights was created by the U.N. after the 1973 Mideast war. A U.N. force of about 1,100 troops had patrolled the area since then.

Israel still controls the Golan Heights, which it captured from Syria during the 1967 Mideast war and later annexed — a move not recognized by most of the international community. Mount Hermon’s summit is divided between the Israeli-annexed Golan Heights, Lebanon, and Syria. Only the United States recognizes Israel’s control of the Golan Heights.