GAZIANTEP, Turkey — Syria pulled both Turkey and Israel closer to military entanglements in its civil war Monday, bombing a rebel-held Syrian village a few yards from the Turkish border in a deadly aerial assault and provoking Israeli tank commanders in the disputed Golan Heights into blasting mobile Syrian artillery units across their own armistice line.
The escalations that threatened once again to draw in two of Syria’s most powerful neighbors came hours after the fractious Syrian opposition announced a broad new unity pact that elicited praise from the big foreign powers backing their effort to topple President Bashar Assad.
“It is a big day for the Syrian opposition,’’ wrote Joshua Landis, a scholar of Syrian political history.
Landis, director of the Center for Middle East Studies at the University of Oklahoma, wrote that the ‘‘Assad regime must be worried, as it has survived for 42 years thanks to Syria’s fragmentation.’’
There has been speculation that Assad, feeling increasingly threatened, may deliberately seek to widen and further complicate the conflict that has consumed much of his own country for the past 20 months and left roughly 40,000 people dead.
Although there is no indication that Assad has decided to try to lure Israel into the fight, any Israeli involvement could rally his failing support and frustrate the efforts of his Arab adversaries.
The attack on the Turkish border, by what witnesses identified as a Syrian MIG-25 warplane, demolished at least 15 buildings and killed at least 20 people in Ras al-Ayn, the scene of heavy fighting for days and an impromptu crossing point for thousands of Syrian refugees clambering for safety into Turkey.
‘‘The plane appeared in seconds, dropped a bomb, and killed children. Here is total chaos,’’ said Nezir Alan, a doctor who witnessed the bombing.
In a telephone interview from Ras al-Ayn, he said the bombing wounded at least 70 people, 50 of them critically, and Turkish TV stations reported that ambulances were rushing victims into Ceylanpinar, Turkey, just across the border.
Windows of shops and houses in Ceylanpinar were shattered by the force of the bombing, and Turkish television footage showed people on both sides of the border running in panic, while military vehicles raced down streets as a huge cloud of smoke hung over the area.
There were no immediate reports of deaths or injuries in Ceylanpinar. But the Turkish authorities, increasingly angered by what they view as Syrian provocations, have deployed troops and artillery units along the border and have raised the idea of installing Patriot missile batteries that could deter Syrian military aircraft from getting close.
In Israel, the military said Israeli tanks that are deployed in the Golan Heights, which the Israelis seized from Syria in the 1967 war, had made a direct hit on Syrian artillery units Monday after consecutive days of erratic mortar fire coming from the Syrian side. The Syrian mortar shells caused no damage or casualties.
Military officials and analysts in Israel said they viewed the Syrian shelling as unintentional spillover from the civil war and that Israel has no desire to get involved in the Syria conflict. But the Israelis have expressed increasing concern that the Assad government may be trying to push them into a fight that could galvanize Arab hostility toward Israel.