Israel shot down a Syrian fighter jet it said had breached its airspace on Tuesday, as Syrian forces reached the Golan Heights frontier for the first time in seven years.

The Israeli military said it monitored the advance of the Syrian Sukhoi fighter jet and shot it down with a pair of Patriot missiles after it penetrated Israeli airspace by about two kilometers (1.2 miles).

Syrian forces have been battling rebels and Islamic State militants at the frontier with Israel in recent weeks.

Tuesday marked the first time government forces reached the border fence with the U.N.’s Disengagement Observer Force at the edge of the Israeli-occupied Golan Heights.

It was the first time Israel shot down a Syrian jet in four years.

Israel’s military said there had been an increase in internal fighting in Syria since the morning hours, including intensified activity by the Syrian Air Force.

Minutes before the reported shootdown, Syria’s state-run Al-Ikhbariya TV was broadcasting footage from the fence demarcating the U.N. buffer zone between Syrian and Israeli forces inside the Golan Heights. A U.N. observer post could be seen just on the other side of the fence.

The camera showed an Israeli post 400 meters (440 yards) away.

Israel captured the Golan Heights from Syria in 1967. The UN deployed a peacekeeping force between the two sides in 1974.

It is the first time government forces have taken up positions along the frontier since an uprising against President Bashar Assad swept through the country in 2011. Islamic State militants later seized territory from rebels along the frontier region.