BEIRUT - Syrian government troops and allied forces reached the eastern city of Deir ez-Zor on Tuesday, breaching a nearly three-year Islamic State group siege on government-held areas of the contested city near the Iraqi border, Syrian state TV and a war monitoring group said.
The TV said troops advancing from the west reached the western outskirts of the city and broke the siege after ISIS defenses collapsed.
Breaching the siege on Deir ez-Zor, which has been divided between an ISIS and a government-held part since 2015, marks another triumph for President Bashar Assad, whose forces have been advancing on several fronts against ISIS and other insurgent groups over the past year.
Tanks and troops had pressed quickly towards a government-held enclave in the city. "The Syrian army and its allies break the siege on Deir ez-Zor," said a military media unit run by the government's ally Hezbollah.
Islamic State still controls much of Deir ez-Zor province, including half the city.
Deir ez-Zor provincial governor Mohammed Ibrahim Samra said government troops were pushing towards the air base.
"Forces are (trying to) break the siege on the military airport as well," he said.
"The coming days will also see the clearing of the city of Deir al-Zor (of militants)" and the start of advances on nearby countryside held by Islamic State, he added.
The latest developments mark a strategic and symbolic defeat for ISIS, which last month lost its hold over Iraq's second largest city of Mosul and is under attack by US-backed Syrian forces in its self-proclaimed capital of Raqqa, northwest of Deir ez-Zor.
Islamic State fighters are believed to have fled to towns around Deir ez-Zor as they came under attack in Raqqa. Both cities lie in oil-rich areas on the Euphrates river.
Syrian troops and allied militiamen, backed by Russia's air force, have for months been advancing toward Deir ez-Zor, the provincial capital of the oil-rich province of the same name. The breach is expected to end a nightmare siege for tens of thousands of people trapped in a handful of neighborhoods controlled by the government and a nearby airport.
Russia's Defense Ministry said Tuesday that a Russian warship in the Mediterranean fired cruise missiles toward Islamic State group targets in Deir ez-Zor province.
A Russian frigate in the Mediterranean Sea fired the missiles early Tuesday on IS targets near the city. The defense ministry said it targeted a fortified area around the town of el-Shola where most of the militants are believed to hail from Russia and former Soviet republics.
The ministry said its drone footage showed that the missile strikes there destroyed a communications center, command centers, ammunition depots, a repair shop for armored vehicles and killed an unspecified number of militants.
Tuesday's breakthrough came after government forces dismantling mines around a besieged government-held air base known as Brigade 137.
The DeirEzzor 24, an activist group that has reporters throughout the eastern province, reported heavy clashes near the village of Jabra that is adjacent to the besieged area.
Tuesday's firing of cruise missiles came a day after the Russian defense ministry said two Russian troops were killed in shelling in Syria's east.
The ministry's statement quoted by Russian news agencies late on Monday said the two men died when a convoy escorting Russian cease-fire monitoring staff came under mortar fire outside the city of Deir ez-Zor.
The ministry said one man died on the spot and the other died later of his wounds in a hospital.
During the long siege, high-altitude air drops have supplied the city. The United Nations said in August it estimated there were 93,000 civilians in government-held parts of Deir al-Zor city, where conditions were "extremely difficult".
Reuters contributed to this report.