Shells fired from Syria landed in Israel in this undated photo.

A mortar shell fired from Syria landed in Israel Monday night amid increased tensions along the two countries’ shared border, as Lebanese media reported that “pro-Palestinian” groups had been given the green-light to retaliate against Israel if the Jewish state conducts any more military operations within Syria.

Israel’s Channel 2 website reported that a military source said the mortar was probably a stray shot following fierce fighting between rebels and government forces near the border, not a bomb aimed at Israeli territory. A Golan Heights Regional Council spokesman said that the surrounding communities were continuing with their regular routine.

Reported Israeli airstrikes on Syrian territory over the weekend prompted a warning from Syrian President Bashar al-Assad that  further Israeli strikes would necessitate a “declaration of war.”

Reports Monday from Lebanese media said that the Syrian government was hesitant to respond with its own manpower in the event it had to act on its threat, fearing that it would take away from its fight with rebels. Instead, it had directed anti-Israel forces along the borders to fire rockets into Israel were the Jewish state to carry out any more military operations within Syria.