Israel shot down a Syrian fighter jet it said had breached its airspace on Tuesday, the Israeli military said in a statement.
The incident occurred as Russian-backed Syrian forces took part in operations against rebels on the edges of Golan Heights, a strategic plateau between Syria and Israel.
The Israeli Defense Forces (IDF) 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 1.2 miles. It was not immediately clear where the plane crashed and no details were given as to the fate of the pilots.
"Since this morning, there has been an increase in the internal fighting in Syria and the Syrian Air Force's activity," the IDF said in a statement.
The Israeli military also said that it would "continue to operate against" any breach of a 1974 U.N. armistice deal that established buffer zones on the Golan. Russian-backed Syrian forces have been battling rebels and Islamic State militants at the frontier with Israel in recent weeks.
The incident comes hours after Israeli Prime Minister Benjamin Netanyahu met with Kremlin officials.
This is the second time Israel shot down a Russian-made Syrian jet. Four years ago, a Sukhoi-24 was shot down with Patriot missiles after entering Israeli airspace. The two Syrian pilots ejected from their aircraft and landed in Syrian territory.
Raytheon's Patriot missile system is designed to track and hunt fighter jets, helicopters, drones and low-flying cruise missiles. The U.S.-made surface-to-air defense system is used by 15 countries and has been deployed to war.
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 interception, Syria's state-run Al-Ikhbariya TV broadcasted 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 440 yards away.
Israel captured the Golan Heights from Syria in 1967. The U.N. 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.
—The Associated Press contributed to this report.