The IDF shot down a Syrian fighter jet that entered Israeli airspace from the Golan Heights border on Tuesday afternoon. Damascus confirmed one of its jets was shot down, but insisted it was taking part in operations against rebels over Syrian territory.
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).
The plane apparently crashed inside Syria, with Sky News Arabic reporting it went down in the Yarmouk area.
"Our air defense systems identified a Syrian Air Force jet that took off from the T-4 Syrian Air Force base and penetrated Israeli airspace. This is a gross violation of the 1974 Separation of Forces Agreement with Syria," he said.
"I have reiterated and made clear that we will not accept any such violation. We will not accept any such penetration of, or spillover into, our territory, neither on the ground nor in the air. Our forces acted appropriately. We insist that the Syrians strictly abide by the Separation of Forces Agreement between us and them."
The IDF also said it was in contact with the Russians during the incident.
As a result of the jet's infiltration, rocket alert sirens blared through the Golan Heights shortly after 1:30pm in the Golan Regional Council, in the Jordan Valley and in the city of Katzrin.
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 UN's Disengagement Observer Force at the edge of the Israeli Golan Heights.
The IDF said that "Since morning hours, there has been an increase in the internal fighting in Syria, including an increase in the activity of the Syrian Air Force."
"During the day, we identified increased aerial activity in the Quneitra area and in the southern Syrian Golan and sent messages through several channels and in several languages about Israel's security interests, according to which we will not tolerate violations of the 1974 Disengagement Agreements," the army added in a statement.
"The IDF is highly prepared to identify any unusual activity threatening our territory and is also prepared for ground and aerial fire," the IDF statement concluded.
This is the second time a Syrian battle plane has been shot down in the last 30 years. Previously, the Israeli Air Force shot down a Syrian fighter jet in September 2014.
Minutes before the reported shootdown on Tuesday, Syria's state-run Al-Ikhbariya TV was broadcasting footage from the fence demarcating the UN buffer zone between Syrian and Israeli forces inside the Golan Heights. A UN observer post could be seen just on the other side of the fence. The camera showed an Israeli post 400 meters (440 yards) away.
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.
Israel used its David's Sling air defense system for the first time on Monday morning in an effort to intercept 2 large Syrian surface-to-surface SS-21 missiles fired as part of ongoing civil war and appeared to be heading towards Israel.
However, one interceptor received an abort order and self-destructed in mid-flight, while the second apparently missed its targets, which hit inside Syrian territory.
David's Sling, which was declared operational over a year ago, is part of Israel’s multi-layered missile defense program and operates in the layer above the Iron Dome and below the Arrow systems.
The Associated Press contributed to this story.