Thousands of Iranian and Iraqi fighters have been deployed in Syria in past weeks to bolster the defenses of Damascus and its surroundings, a Syrian security source told AFP on Wednesday.
"Around 7,000 Iranian and Iraqi fighters have arrived in Syria over the past few weeks and their first priority is the defense of the capital. The larger contingent is Iraqi," the source said on condition of anonymity.
"The goal is to reach 10,000 men to support the Syrian army and pro-government militias, firstly in Damascus, and then to retake Jisr al-Shughur because it is key to the Mediterranean coast and the Hama region" in central Syria, he added.
Syria's government lost control of Jisr al-Shughur in northwestern Idlib province on April 25, as a coalition of opposition forces including Al-Qaeda affiliate Al-Nusra Front swept through the region.
Yesterday, Iran's official news agency IRNA quoted elite Revolutionary Guards General Qassem Soleimani as saying "in the coming days the world will be surprised by what we are preparing, in cooperation with Syrian military leaders."
The agency cautioned however that it "takes no responsibility for the information."
Iran is a key ally of the Syrian government, and it has provided Damascus with financial and military support throughout the conflict that began in March 2011 with anti-regime protests.
That support has included raising a Syrian pro-government militia known as the National Defense Force (NDF) to supplement the badly-stretched regular Syrian army, as well as sending battalions of fighters from the Hezbollah terrorist group, Tehran's most important and powerful proxies.
Iran had also coordinated the training, arming and mobilization of Iraqi Shia Islamist militias to fight alongside Syrian government forces as well - though since the Islamic State's lightening offensive through Iraq last summer most have returned home from Syria to fight ISIS there.
Iran has also sent an unknown number of soldiers and commanders from its own elite Revolutionary Guard corps to battle Syrian rebels.
But despite all that aid, in recent months the Syrian government has lost territory in several parts of the country to both an alliance of largely Islamist groups including Al-Nusra, and to the Islamic State (ISIS) jihadist group. In the south of the country as well, a more moderate rebel alliance has been making steady gains.
The rapid succession of defeats have led many to speculate the Assad regime may be nearing its demise, although other analysts have warned it is far too early to write it off yet.
Faced with those setbacks, the government has appealed to Tehran and ally Russia to step up support, a Syrian political figure close to the regime told AFP.
A diplomatic source in Damascus said Iran had been critical of the regime's failure to achieve the last major offensive operation it undertook - a February bid to cut rebel supply lines to the northern city of Aleppo.
Tehran had opposed the operation, citing lack of preparation, the source said, and subsequently insisted that Syria change its strategy to focus on holding less territory more securely.
Analysts and observers have said the Syrian government now appears ready to accept the de facto partition of the country, focusing on the defense of strategically important areas and leaving others to rebels or jihadists.
According to one source close to the regime, it considers the coast, the central cities of Hama and Homs, and the capital Damascus as vital.
It also regards the Damascus-Beirut and Damascus-Homs highways as "red lines", the source said.
More than 220,000 people have been killed in Syria's civil war.
AFP contributed to this report.