BEIRUT (AP) — Syrian troops and allied forces reached the eastern city of Deir Ezzor on Tuesday, breaching a three-year-old Islamic State siege on parts of the contested city near the Iraqi border, Syrian state TV and a war monitoring group said.

Lifting the siege on Deir Ezzor, parts of which have been ruled by the extremist group since January 2015, marks another victory for President Bashar Assad, whose forces have been advancing on several fronts against IS and other insurgents over the past year.

It also puts an end to a humanitarian crisis for the estimated 70,000 people who survived on erratic air drops of food and supplies during the 32-month siege. Syrian state media said dozens of trucks carrying aid are ready to move in.

The TV said troops reached the western outskirts of the city and broke the siege after IS defenses collapsed. Rami Abdurrahman, who heads the Britain-based Syrian Observatory for Human Rights, also reported that troops had breached the siege.

The militants “did give up easily and used lots of suicide car bombs yesterday, but could not resist much,” said opposition activist Omar Abu Laila, who currently lives in Europe but is from Deir Ezzor and is in contact with people there.

IS has suffered a series of major setbacks in recent months. Iraqi forces drove the extremists from the northern Iraqi city of Mosul in June, and US-backed Syrian forces have seized more than half of the Syrian city of Raqqa, once the group’s self-styled capital.

Syrian troops and allied militiamen, backed by Russia’s air force, have for months been advancing toward Deir Ezzor, the provincial capital of the oil-rich province of the same name.

An exiled Deir Ezzor resident and former opposition fighter, whose family has remained in the city in IS-controlled areas, welcomed the lifting of the siege but expressed concern over the fate of civilians in IS-controlled areas. He spoke on condition of anonymity, fearing for the safety of his family.

Deir Ezzor is in the Euphrates River Valley, which stretches all the way to the Iraqi border, taking in several towns and villages, and is the largest remaining IS stronghold. The extremists still control around 60 percent of the city, and it could take Assad’s forces months to drive them out.

The offensive that led to breaking the siege was led by General Suheil al-Hassan, who is known as the Tiger. Al-Hassan has been behind much of recent victories by government forces, including the capture of eastern parts of the northern city of Aleppo in December, the government’s biggest victory since the conflict began in March 2011.

Assad’s office released a statement saying he had called to congratulate the commanders who were defending the city.

Russia’s Defense Ministry said a Russian warship in the Mediterranean fired cruise missiles early Tuesday toward IS targets near the city. The 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 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 dismantled mines around the once besieged government-held air base known as Brigade 137.

DeirEzzor 24, an activist group that has reporters throughout the eastern province, reported heavy clashes near the village of Jabra, adjacent to the besieged area.