In their latest meeting on November 11, U.S. President Donald Trump and Russian President Vladimir Putin affirmed joint implementation of an early July ceasefire plan to establish a “de-escalation zone” in southwestern Syria. More precisely, the zone, meant to reduce fighting in southwestern Syria, covers Daraa province bordering Jordan and Quneitra province bordering the Israeli-occupied Golan Heights.

While the arrangement has helped stabilize Syria and reduce the scale of violence between conflicting factions, it has sounded alarm bells in neighboring Israel.

Israeli leaders are concerned that the scheme will afford Iran, its regional arch foe, an unprecedented opportunity to carve out a foothold in Israel’s backyard in the wider Golan region.

Indeed, the Islamic Republic has, ever since its establishment in 1979, confronted Israel by proxy only, that is, through Lebanese Hezbollah and Palestinian groups such as Hamas and Islamic Jihad. Now Iran has found itself, for the first time over the past four decades, only a few kilometers from Israeli territory.

Once consolidated, such a position would be decisive for possible conflicts in the future between Israel and Iran or its allies. As Israeli Intelligence Minister Yisrael Katz indicated during a security conference in Tel Aviv on September 11, in the event of military confrontation, Iran will be able to deploy “tens of thousands of Shia militiamen … from various countries” on Israel’s northeastern borders.

To prevent this from happening, Israel has adopted a multi-pronged strategy that consists of efforts to target Iranian Revolutionary Guards and allied militias at the Quneitra and Golan regions, and to intercept the transfer of advanced weaponry to Hezbollah, including midrange missiles. The Israeli strategy to counter Iran has been pursued systematically since the tide of war turned in favor of the Bashar Al-Assad regime following the recapture of Aleppo in late December 2016, though it has been in place for a longer time.

One of the most significant and provocative developments along these lines took place on January 18, 2015, when Israeli jets struck a convoy in Mazraat Amal in the Quneitra region. The airstrike killed six Hezbollah and Iranian Revolutionary Guards members.

Less than two weeks later, on January 30, Hezbollah retaliated by launching an ambush rocket attack against an Israeli convoy near the border with Lebanon that left two soldiers dead.

In September 2017, Israeli jets allegedly targeted a military facility near the northwestern town of Masyaf in Syria’s Hama province, where the Syrian government was thought to be producing chemical weapons and storing surface-to-surface missiles. The attack, carried out shortly after the initial U.S.–Russian agreement on the creation of “de-escalation zones” in Syria, was intended to send a signal of dissatisfaction to both Washington and Moscow.

Notably, in late August, the chief of Mossad Yossi Cohen had paid an official visit to the White House to inform the Trump administration of Israel’s objections to the scheme. Almost simultaneously, Israeli Prime Minister Benjamin Netanyahu met with Putin in Sochi to raise concerns about the possibility of Iranian military consolidation in southwestern Syria.

Moscow supports the de-escalation scheme basically because it wants to end the conflict on its own terms, which will confer on Russia the status as a superpower to reckon with and—unprecedented in its history—as a global peace-broker.

For the Trump administration, on the other hand, the top priority is defeating the Islamic State and helping Kurds carve out their own foothold in the northeast as a sort of American surrogate that will protect U.S. interests in Syria. While Iran’s actions in Syria are of great importance to the United States, they do not seem to be understood in Washington as threatening vital U.S. interests. This is, of course, not the case for Israel.

Sources close to Syrian opposition groups have repeatedly warned about the presence of Iranian forces and Shia militia groups in the Quneitra region.

Hezbollah Al-Nujaba, an Iran-backed Iraqi paramilitary outfit, is one of these groups that has gone so far as to form a “Golan Liberation” unit within its ranks and declared its readiness to “liberate the Golan” from Israeli occupation. The first public announcement of this came in March 2017, that is, shortly after the recapture of Aleppo, which relieved Iran-backed militia forces stationed in northwestern Syria of a formidable battlefield challenge and thus enabled them to concentrate their manpower and firepower alike on the southwestern and eastern fronts.

Iran-orchestrated moves in western Syria are not limited to militia mobilization. Western intelligence sources have claimed that Iranian forces have been trying to establish a permanent military base near Damascus. Satellite images have spotted construction activity at a site outside Al-Kiswah south of Damascus, formerly used by the Syrian Arab Army. Notably, Israeli missiles hit the Al-Kiswah compound on December 2, reportedly leaving a number of Iranian soldiers at the site dead and wounded.

Apart from relying on its air force, Israel is also working with Syrian rebel groups—like Fursan Al-Joulan or Golan Brigade—to create a “buffer” against Iran-backed militias in the Quneitra province. The cooperation mainly includes provision of medical services, financial assistance, and intelligence sharing. There are also reports about Israeli collaboration with such extremist groups as Ahrar Al-Sham and Hayat Tahrir Al-Sham (formerly Nusra Front) and even the Islamic State to push back against pro-Assad forces.

The fact is that Iranian military or paramilitary entrenchment in southwestern Syria will enable it to open a new front against Israel on its northeastern borders in the event of conflict. Coupled with established Hezbollah presence in southern Lebanon—which overlooks northern Israeli territory—this development can effectively change the balance of power between the two regional nemeses in favor of Iran.

Maysam Behravesh is a PhD Candidate in the Department of Political science and an Affiliated Researcher in the Center for Middle Eastern Studies (CMES), Lund University, Sweden. On Twitter: @behmash