In recent weeks, Israel has stepped up its discreet campaign to obstruct Iranian moves to build large military bases and missile factories in Syria.

There have been no reports of air strikes in Syria by Israel since an air battle on February 10 that was sparked by the incursion of an Iranian drone into Israeli air-space.

But Israeli diplomats and intelligence officials have been briefing foreign counterparts and media about the Islamic Revolutionary Guards Corps’ (IRGC) actions in Syria.

This campaign is designed both to create international pressure to curb Iran’s plans and send Tehran the message that Israel is monitoring its movements closely and will launch further strikes if necessary.

The information on Iran’s bases in Syria featured in a report this week by Bicom, the pro-Israel advocacy group.

It included the locations of ten Iranian bases currently operating in Syria and a breakdown of pro-Iranian forces, which could total as many as 40,000 Shia fighters from Iran or under Iranian control.

The most recent Israeli intelligence assessments suggest there actually was a reduction in Iranian-backed forces in Syria as the Assad regime has been gradually rebuilding itself.

Israel also believes that, while the IRGC has not given up its plans to establish a large, permanent presence in Syria, the bases are not yet built for long-term operations.

There are three reasons for this apparent hesitation by the IRGC: first, it is clear that Israel will bomb the bases in future as it did on February 10.

Second, there is a debate under way in the Iranian leadership on its role in Syria.

President Hassan Rouhani is known to oppose spending hundreds of millions, perhaps billions, on Syrian bases, when the money is needed for propping up the country’s shaky economy.

Russia is the third factor holding back Iranian ambitions in Syria. Although keen to use Iran’s men as “boots on the ground” in lieu of its own ground forces, the Kremlin has been trying to balance Israel and Iran.

It allowed the Iranians to remain but blocked their more ambitious plans and did not permit a presence within ten kilometres of Israel’s Golan border.

But Iran appears to be chafing at the restrictions and Israel may not be content to wait for Vladimir Putin to rein them in. The prospects of further escalation between the two countries on Syrian soil have greatly increased over the past few weeks.