The Israeli military struck artillery positions in Syria on Tuesday after a projectile from that country's civil war hit the Israeli-controlled part of the Golan Heights, but denied a Syrian claim that Syrian forces shot down two Israeli aircraft in the assault.

The incident was the fifth case since last week in which fighting in Syria has spilled over into Israeli territory, and the first since a U.S.-Russian brokered truce went into effect at sunset on Monday to try to end Syria's war, now in its sixth year.

Israel has largely remained on the sidelines of the fighting, but has carried out reprisals on Syrian positions when errant fire previously landed in Israel.

Shortly after the air raid, Syria's armed forces claimed to have shot down an Israeli warplane and an unmanned drone along the frontier between the countries.

The Israeli military quickly denied the report, saying that a pair of surface-to-air missiles were fired at its aircraft but missed. "At no point was the safety of IDF (Israel Defense Forces) aircraft compromised," it said.

Israeli warplanes have conducted several air raids on Syrian army positions over the past weeks after stray shells hit the Israeli-controlled area. Israel is also widely believed to have carried out airstrikes on arms shipments said to be destined for the Lebanese militant group Hezbollah, a close ally of the Syrian government.

Israel captured the Golan Heights from Syria in the 1967 Mideast war and the two countries have been at a state of war for decades.