(Reuters) Israeli aircraft attacked targets in Syria on Tuesday, hours after a stray mortar bomb from fighting among factions in Syria struck the Golan Heights, the Israeli military said.

The strike came hours after a nationwide ceasefire in Syria brokered by the United States and Russia went into effect on Monday evening, the second attempt this year by Washington and Moscow to halt the five-year-old civil war.

No casualties from the mortar bomb that hit Israeli-held territory on Monday evening were reported and the military said in a statement “aircraft targeted artillery positions of (the) Syrian regime in the central Syrian Golan Heights”.

The area is close to where fighting in the Syrian civil war has been taking place. Israel has responded similarly in the past when there has been an overspill of fire into the territory.

The previous retaliation for errant fire took place on Saturday when Israeli aircraft struck Syrian positions. A military spokeswoman said Tuesday’s strike was the fourth retaliation since Sept. 4.

Israel captured the Golan, a strategic plateau, from Syria in the 1967 Middle East war and annexed it in 1981 in a move that has not won international recognition.