In recent days, following continuous bombardment, including airstrikes against a Turkish military convoy last Monday, Syrian regime forces have advanced into opposition-controlled areas of northern Syria. For the first time in five years the regime has entered Khan Sheikhoun, which is strategically located on Syria’s international highway in southern Idlib Governorate.

If forces loyal to Syrian President Bashar al-Assad continue their advance, many of the 3 million Syrians in Idlib might flee toward Turkey, which already hosts 3.5 million refugees. In fact, the United Nations regional humanitarian coordinator for the Syria crisis, Panos Moumtzis, has anticipated that 2 million Syrian refugees might flee into Turkey. This would trigger another humanitarian crisis on the scale of what took place in 2011–2013, when millions of Syrian refugees poured into Lebanon, Jordan, and Turkey.

The political implications for Turkey could be immense, as the Syrian refugee crisis continues to play a major role in domestic debates. Following his party’s two consecutive defeats in Istanbul’s mayoral elections, President Recep Tayyip Erdoğan is keen to keep a lid on the Syrian crisis across the border. Turkey has been working on returning thousands of refugees to Syria, forcibly in most cases. Therefore, a new wave of refugees could prove detrimental to Erdoğan’s Justice and Development Party, as well as to his political legacy.

The desire to avert a new flood of refugees will most likely compel Ankara to try to reverse the advance of Syrian forces. Direct intervention remains less likely, except to protect a besieged Turkish observation post near Khan Sheikhoun or if the so-called Syrian National Army (SNA), created by Turkey and made up of Syrian opposition combatants whom the Turks have armed, trained, and financed, fails to halt the Assad army’s advance. However, thrusting the SNA into battle with the Syrian regime requires a shift in strategy. It was created not to fight the regime but Kurdish forces further east. Skirmishes occur regularly between the SNA and the Kurdish-led Syrian Democratic Forces, with Turkey’s military providing artillery cover for its allies. That is why Ankara would have to give events in Idlib greater priority to avert a new humanitarian crisis.

Since its creation in May 2017, the SNA has grown from a few thousand combatants to more than 35,000 today. It is the largest and best equipped fighting force on the opposition side and its expansion and training owes much to the so-called “safe zones” in northern Syria that Turkey has carved out through its Euphrates Shield and Olive Branch operations. Given the failure of previous attempts to unite Syrian rebel forces, maintenance of the SNA has been a success for the Turkish military and intelligence services, giving Ankara important leverage over whatever happens in Syria.

Yet Turkey’s investment in the SNA would be at risk if the Syrian army succeeded in recapturing Idlib Governorate. This would help the Assad regime focus next on areas controlled by Turkey, which would not only threaten Ankara’s aim of returning Syrian refugees to Syria, but also have consequences for Turkish plans to expand eastwards into areas controlled by Syrian Kurdish forces. It would put Turkey on the defensive in Syria, with little latitude to act against what it perceives to be a Kurdish threat to its own national interests.

Turkey appears to be paying the price for its contradictory alliances. It has moved closer to Russia lately, deploying the Russian S-400 air defense system against the United States’ preferences and collaborating with Moscow in finding a solution to the Syrian conflict. However, Ankara has also sought to avoid a confrontation with Washington over Kurdish-dominated areas, where U.S. forces are deployed alongside Kurdish fighters. Turkey had threatened to invade those areas, a move the United States has opposed, but the two compromised recently by setting up a joint operations center allowing them to coordinate their actions.

On August 16, Turkish Defense Minister Hulusi Akar declared that “the U.S.-Turkish joint operations center set up in Turkey’s southeastern Sanliurfa province to work on a planned safe zone in north and east Syria will begin full operations next week.” This seems to have been a major reason for why Russia supported the Assad regime’s offensive in Idlib, both by hitting targets with its own aircraft and by supplying the Syrian military with improved weaponry, including night vision equipment. The Syrian Air Force’s bombing of the Turkish convoy is also likely to have followed Russian approval.

In other words Moscow appears to fear the consequences of a U.S.-Turkish agreement over northeastern Syria. If this paves the way for a longer-term U.S. and Turkish presence in the country, it could negatively impact on Russia’s influence there and on the Assad regime it has upheld. That is why the Russian and Syrian regime offensive in Idlib has been designed to turn the tables on Turkey and the United States. Northern Syria is a viper’s nest in which all events are linked and anyone can be bitten. This volatile situation won’t soon end.