If it goes ahead, Iran likely will view President Donald Trump's decision to withdraw American forces from eastern Syria as a green light to build a new war machine in the region.
But Iran also received a red light recently, apparently reminding it that Israel is standing guard against Tehran's takeover plans.
That red light came Dec. 25 in the form of an alleged Israeli air strike on an Iranian weapons depot in Syria. The strike looks like the latest signal of Israel's determination to block Iran's path into Syria, with or without an American ground presence.
According to media reports, including a report by the Israeli satellite image company ISI, the strike destroyed a warehouse that contained Iranian Fajr-5 rockets. The warehouse was just 40 kilometers – about 25 miles – away from Israel.
Israel's military says Fajr 5 rockets are produced in Iranian weapons factories and have a range of 75 kilometers, or just under 50 miles. In past years, Iran smuggled these types of rockets to terrorist organizations that are ideologically committed to attacking Israel, including Hizballah in Lebanon and Hamas in the Gaza Strip. Now, Iran is trying to flood Syria with them.
So far, the Fajr 5s that have been in the inventory of Israel's enemies were unguided rockets. That does not stop them from posing a serious threat. Hamas fired a Fajr 5 rocket in November 2012 in the midst of an eight-day conflict, severely damaging an apartment building in Rishon Lezion, south of Tel Aviv. Residents survived due to an air raid siren, which sent them scurrying into a safe room before the rocket struck.
In February 2017, reports emerged saying that Iran's defense industry has begun manufacturing a new, guided version of the Fajr 5.
These can be fired quickly and in succession from a multiple launch rocket system (MLRS). The arrival of such weapons would present terrorists in Syria seeking to attack Israel with new precision abilities.
It remains unclear whether the Fajr 5 rockets destroyed in the alleged Israeli strike were guided, but Israel has drawn a clear red line that forbids the arrival of Iranian guided projectiles in the area. Once in Syria, precision weapons can be given to Shi'ite militias under Iran's command, or be used by Iranian military forces themselves, which are operating on Syrian soil. That's what happened last May, when Islamic Republican Guards Corps (IRGC) used a truck-mounted rocket launcher to fire on the Golan Heights.
In other cases, batches of Iranian weapons that have made their way into Syria are subsequently smuggled into neighboring Lebanon, where Hizballah has built up one of the world's largest arsenals of surface-to-surface projectiles. Hizballah's estimated 130,000 rockets and missiles are pointed at Israeli cities, power plants, ports, airports, and military installations.
Thus, Iran has already turned Lebanon into a forward military post against Israel. Its goal now is to do the same in Syria.
Although the U.S. forces stationed in Syria are there exclusively to combat Salafi-jihadist Sunni ISIS terrorists, their presence in the strategically important Al-Tanf region, on the Syria-Iraq border, also helps block the expansion of the radical Iranian-Shi'ite axis.
The U.S. presence has helped stop Iran from trying to use the Al-Tanf border crossing as a gateway for land convoys carrying Iranian weapons and Shi'ite militias, from Iraq into Syria.
The Al-Tanf border area is one of two ground corridors that Iran is hoping to use in its Syrian expansion project.
The second main land 'entrance' to Syria is located further north, at the Albu Kamal border crossing. This area has been the scene of repeated Iranian and Hizballah-controlled traffic of militias and weapons. But this site also drew at least one major alleged Israeli strike in June, resulting in dozens of casualties, including Iranian military officers and Iraqi Shi'ite militia members.
Currently, Israel and Iran remain locked in a shadow war over Syria's future. Israel is employing preventative force to stop Iran from converting Syria into second front, alongside Lebanon.
Tehran's takeover efforts are being led by the IRGC, which acts as the 'long arm' of Iran across the region, particularly through the overseas expeditionary elite unit, the Quds Force, commanded by the notorious General Qassem Soleimani.
With Israel 'covering' the northern Albu Kamal crossing, the U.S. had been 'covering' the southern Al-Tanf crossing, meaning that Iran's ground expansion scheme had run into some difficulties. Iran was forced to rely on its more traditional trafficking method – cargo flights – though this too had become increasingly difficult, with Israel monitoring suspicious flights around the clock, and reportedly taking action when intelligence called for it.
A U.S. withdrawal from Al-Tanf, however, would be seen by the Iranians as a gap in the fence. This can be seen from a statement made by Jaafar al-Husseini, the military spokesman of Kataeb Hizballah, an Iraqi Shi'ite militia backed by Iran, which maintains a presence in the Albu Kamal region. According to the Meir Amit Intelligence and Terrorism Information Center, al-Husseini said his militia "is willing to take part, along with the Syrian Army, in protecting the Syrian Kurds along the border with Iraq," following Trump's withdrawal announcement.
The Kurds in eastern Syria would become vulnerable to Turkish attacks if the U.S. leaves, and they would likely reach out to Assad and perhaps even the Iranians in desperation. Al-Husseini's remarks are really an expression of an Iranian intention to fill a vacuum.
Al-Husseini told the Hizballah-affiliated Lebanese Al-Mayadeen television station that "we have an ongoing and highly active relationship with Kurdish commands in northern Syria. We have the full picture regarding what is happening in northern Syria, including the movement of the American [forces]." Such comments reflect a keen Iranian appetite to move into eastern Syria.
Russia will be equally keen to fill in the vacuum, but since it still depends on the Iranian axis for help in stabilizing the Assad regime, Tehran and Moscow can be expected to try and reach an agreement over how to proceed.
Comments made last week by the outgoing Israel Defense Forces (IDF) Chief of Staff, Lt.-Gen. Gadi Eizenkot reflect just how central the threat of an Iranian takeover of Syria has become in the eyes of the Israeli defense establishment.
"The main topic over the past years for the IDF has been the Iranian entrenchment in Syria," Eizenkot said, during one of his final public addresses in uniform.
In Syria, he said, Iran has been trying to build an army of 100,000 Shi'ite militia members, including Hizballah operatives. It has tried to construct missile bases, and a create chain of attack positions on the Syrian border with Israel. Hundreds of Israeli strikes prevented this from happening, the Israeli military chief added.
In next-door Lebanon, Iran and Hizballah planned for a ground invasion of a strip of 5 kilometers in northern Israel, using attack tunnels, to "create an achievement that would reverberate in history," Eizenkot said. The IDF exposed and demolished Hizballah's cross-border attack tunnels in recent weeks, foiling that dangerous plan.
Iran and its Lebanese proxy have also made "a very big effort to create precision firepower, and level the playing field with what Hizballah perceives to be Israeli military superiority," Eizenkot stated.
"The security challenge is like a very big iceberg. Some of it is visible to public and media [but] most of it is hidden from view. In the hidden part, the IDF is very busy with the multi-dimensional Iranian threat, and the Hizballah threat. The War Between Wars [Israel's preventative campaign] has turned into a central effort," he added.
Iran has invested $16 billion in rescuing Assad, and deployed 2,000 IRGC military advisers to the country. It has reportedly sustained more than 1,000 casualties, and mobilized around 10,000 Shi'ite militia members, most from Iraq and Afghanistan. These fighters have been joined by 8,000 Lebanese Hizballah members. Hizballah, too, has paid a heavy price in Syria, losing an estimated 2,000 casualties.
The scale of this investment suggests that the Islamic Republic is not about to give up on Syria. At the same time, Iran faces major financial pressure from re-imposed American sanctions. So far, Iran has been able to suppress domestic protests, and navigate the sanctions, while remaining committed to expansion in Syria.
Iran likes to pretend that it is in Syria at Assad's invitation, but in reality, the Damascus regime owes its existence to Iranian life support, and has little choice but to grant every Iranian 'request' to use its territory.
Iran's ultimate goal is to encircle Israel with bases of missiles and terrorist armies, a sentiment made clear by comments made Sunday by Tehran's Palestinian proxy group, Palestinian Islamic Jihad (PIJ), which is the second largest armed faction in the Gaza Strip.
Speaking from Tehran, PIJ secretary-general Ziad Nakhla said, "In any future war, the resistance axis will act as one man, from north to south. Israel must understand that the resistance axis today is one."
Yaakov Lappin is a military and strategic affairs correspondent. He also conducts research and analysis for defense think tanks, and is the Israel correspondent for IHS Jane's Defense Weekly. His book, The Virtual Caliphate, explores the online jihadist presence.