Steady advances by insurgents on key fronts in Syria mean President Bashar al-Assad is under more military pressure than at any point in the four-year-old war.

Losses in the north, east and south to groups including al Qaeda’s Syrian arm and Islamic State may test Assad’s hold over western parts of the country that are the most crucial to his survival.

After his loss of Palmyra, a symbolic and militarily strategic city, and nearly all of Idlib province, he appears to be circling his wagons more closely to a western region that includes Damascus, Homs, Hama and the coast.

Sources familiar with the thinking in Damascus acknowledge that pressure is growing but say the government is confident the army can defend crucial territory with the help of its allies.

Assad still controls areas in more far-flung parts of Syria, but these are dwindling in number. His decision to maintain forces in places such as in Deir al-Zor, Hasaka and Aleppo suggests he still wants to preserve a nationwide presence, rejecting Syria’s de facto partition.

The summer will be tough on the ground, but red lines will not be breached

Sources familiar with the government’s thinking say Assad is confident about standing his ground: extra support is expected from Iran, his strongest ally, which said it would continue to stand by Syria. The Lebanese group Hezbollah, which is backed by Iran, is more widely deployed in Syria than ever.

And Assad still believes the West will eventually rehabilitate him as a partner in the fight against Islamic State – a shift that shows no sign of happening but which he thinks is inevitable given the risk of a full jihadist takeover.

A rebel fighter with his weapon sheltering at a building in Soran Azaz, Aleppo, yesterday.A rebel fighter with his weapon sheltering at a building in Soran Azaz, Aleppo, yesterday.

“The summer will be tough on the ground, but red lines will not be breached,” said one source familiar with the thinking in Damascus, declining to be named because he was discussing private conversations with Syrian officials.

Assad has survived such pressure before, notably at the end of 2012 when the West thought his government was near collapse. But the difference now is that the insurgents have grown in strength while government forces have been weakened after more than four years of fighting.

Assad has also lost Iraqi Shi’ite militiamen who had been fighting alongside Syrian forces. They went home to fight Islamic State after it captured Mosul and other Iraqi cities last June. The sudden advances also added to the military pressures facing Iran both in Syria and Iraq.

Insurgent groups in the north and south of Syria have emerged as the war’s most dynamic force in the past two months. They are better organised and armed than before and are believed to have received new support from Assad’s regional enemies.

Lebanon’s As-Safir newspaper yesterday said more than 20,000 Iraqi, Iranian and Lebanese fighters had entered Idlib province in readiness for a counter attack.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.