BEIRUT -- A series of coordinated blasts hit bus stations, an electricity plant and a hospital across two Syrian cities Monday, killing at least 80 people in the first major security breach of President Bashar Assad's coastal strongholds in the country's five-year war.
The Islamic State militant group claimed responsibility on social media for the attack. The militants are not known to maintain a presence in the surrounding countryside, an area in which mainstream rebels and al-Qaida-affiliated insurgents form the predominant opposition to Assad's forces.
The seven closely coordinated morning blasts in the pro-government cities of Tartus and Jableh targeted civilians in large numbers.
They also underlined the inability of world powers to jump-start Syrian peace talks in Geneva as the violence worsens.
A coalition of nearly 30 rebel factions said Sunday that they would give the government 48 hours to end its offensives around besieged opposition-held suburbs of Damascus or they would consider the partial cease-fire brokered in late February "dissolved." Yet fighting had already resumed in earnest around the country by late April.
The peacefulness of the two coastal cities meant they housed hundreds of thousands of internally displaced people who fled violence in other parts of the country -- and who are now coming under suspicion by long-term residents and government security forces.
The state-owned Syrian Arab News Agency reported that four explosions struck Jableh, the result of three suicide attacks and a car bomb. The targets included the emergency entrance of the Jableh National Hospital, it said.
Shortly afterward, suicide bombers followed by an explosives-laden car tore through a packed bus station and a petrol station in Tartus, minutes apart, TV reports and residents said. More than 38 people were killed and many injured in those blasts, Syrian state media reported.
The Syrian Observatory for Human Rights, an opposition monitoring group based in Britain, put the death toll much higher than Syrian government sources, saying that more than 145 had been killed.
The four explosions in Jableh and three in Tartus ripped through both locations almost simultaneously, indicating a high degree of organization.
They sparked a backlash against the displaced, including a reprisal attack on a camp in Tartus. Parts of the al-Karnak camp were burned down, according to Ghassan Hassan, who heads the Tartous2day media agency.
Some 700,000 refugees from the war-torn Aleppo, Idlib, and Raqqa governorates are settled in Tartus, Hassan said. Security forces arrested dozens of refugees in sweeps of Jableh and Tartus, the Observatory reported.
Russia, which is heavily invested in the Syrian war on behalf of Assad's government, keeps a naval base in Tartus, the only such base on the Mediterranean. It also has an air base in Latakia province, about three miles north of Jableh.
Russian President Vladimir Putin's spokesman said the increase in militant attacks and bombings in Syria "once again demonstrates how fragile the situation in Syria is." Putin sent a message to Assad conveying his condolences for the civilian deaths and confirming Russia's readiness to continue supporting its "Syrian partners."
Assad's government and the government of his father, who ruled the country from 1971 until his death in 2000, have historically drawn on the coastal provinces for political support.
They are home to a sizable population of Alawites, the religious minority to which the Assads belong. Assad has been keen to project an image of stability in these strongholds.
But the region has also been the backdrop to some of the war's darker junctures, including twin massacres in Baniyas and Bayda, two formerly restive towns about 25 miles north of Tartus. Pro-government forces or militias summarily executed 248 civilians and looted and burned down Sunni neighborhoods in May 2013, according to Human Rights Watch.
Moderate and ultraconservative Sunnis now form the backbone of the insurgency against the government in the surrounding regions.
United Nations Secretary-General Ban Ki-moon condemned the attacks on civilians in Tartus and Jableh. Ban was also concerned about escalating military activity in and around Damascus and Homs, which is causing a rising number of civilian casualties, his spokesman Stephane Dujarric said.
According to the U.N., Syria's civil war has displaced more than 11 million civilians since March 2011 and has killed more than 250,000 people -- but the international organization stopped collecting figures in mid-2015.
Information for this article was contributed by Albert Aji, Sarah El Deeb and Zeina Karam of The Associated Press.
A Section on 05/24/2016