It appears the Syrian civil war is entering its final stages. On Sept. 5, Syrian loyalist forces, in close conjunction with Iranian and Russian military forces, broke the Islamic State's three-year siege on the loyalist forces in Deir el-Zour. The arrival of the relief force in the city is one of the biggest developments on the Syrian battlefield since the loyalists captured Aleppo city, and heralds the extent to which government forces have gained the upper hand in the Syrian civil war since a year ago.
On the same day the loyalists forces reached Deir el-Zour, Israel began its largest military exercise since 1998. The combined arms exercise focuses on preparing for a potential war with Hezbollah along Israel's northern border, and is set to run for 10 days and involves tens of thousands of Israeli troops. The exercise, though planned more than a year in advance, is not unconnected to developments in Syria. Israel has been keenly observing the Syrian battlefield, deeply concerned by the momentum the Iran- and Russia-backed loyalist forces have seized over the past year.
He Who Controls Syria (and Its Borders)
Israeli leaders are increasingly aware that the Syrian civil war has reached the beginning of its end phase. As the conflict draws down, with Syrian troops reasserting their control over much of the country, Hezbollah will no longer be overstretched and encumbered by its massive involvement in the fighting. Hezbollah would in effect be able to redeploy its forces to Lebanon, boosted by years of tough combat experience as well as increased arms and equipment backing from Syria and Iran.
The relief of the Deir el-Zour garrison also factors into the increased support Hezbollah is expected to receive going forward: Retaking the city presages the completion of the logistical supply line running from Iran through Iraq to Syria and then to Lebanon. The arrival of Syrian loyalists at the Iraqi border isn't imminent: The loyalists still need to consolidate control over the city, fend off Islamic State counterattacks and cross the Euphrates River. Still, with the Iraqi border located less than 100 kilometers (62 miles) east of Deir el-Zour through sparsely populated terrain, the arrival of the loyalist forces there is more certain than ever.
Contending with this loyalist advance eastward are tribal Arab fighters of the Syrian Democratic Forces (SDF), a few thousand of whom are positioned around al-Shaddadi to the north. These U.S.-backed forces have made their ambitions to drive southward clear, and may end up skirmishing with loyalist forces on their way to the Iraqi border. The area also has many critical natural gas and oil fields, which will drive competition — and fighting — further. But the balance of forces in the area is decisively tilted toward the loyalists. And absent direct and sustained U.S. military action in support of an SDF drive south that pushes back loyalist attempts to advance (with all the ramifications such a move would have with Iran and Russia), the loyalist forces should be able to seize the energy fields and reach the Iraqi border east of the Euphrates River. Even in the unlikely event that the loyalist forces are impeded, they will still be able to secure a supply line to Iran by seizing the road through al-Bukamal further to the south that runs into Iraq at a border location on the west bank of the Euphrates River.
A More Aggressive Approach
With a direct Iranian land route to Lebanon all but certain and with the militant group able to draw down its commitments in the Syrian civil war, Israel faces the increased prospects of having to again face off against a stronger Hezbollah. The window in which Israel could attack Hezbollah while it's still distracted and overstretched with its commitments in Syria is closing. So, as Israel conducts its largest military exercise in 20 years, it's worth remembering that the military preparations are not entirely defensive. Tel Aviv will likely adopt a more aggressive approach toward Hezbollah in the coming months.
The extent of this approach depends on the calculations Israeli leaders make. The response could range from simply intensifying strikes on Hezbollah convoys to launching an outright preventive war against Hezbollah's missile and rocket stockpiles in Lebanon. Even if Israel only increases the scope of its airstrikes on Hezbollah positions in Syria, the likelihood of a full Israeli-Hezbollah conflict is very high, if not inevitable, especially as an emboldened Hezbollah would find it necessary to retaliate to deter further Israeli attacks. The Syrian civil war, then, could lead to another regional conflict, even as it reaches its end stages.