The twin crises in Syria and Iraq are altering the region’s battlefields and geopolitical dynamics. Russia, Turkey, Iran, the Assad regime, and ISIS are sweeping in as U.S. troops withdraw from northeastern Syria. In neighboring Iraq, widespread popular protests are creating military and political opportunities for Iran and its proxies. Here are some of the grim implications for U.S. national security:

The United States will be less able to target terrorists planning external attacks from Syria. The American military withdrawal cedes greater control over Syria’s airspace to the Russian military. Airstrikes have been the primary weapon the U.S. employs against terrorists in Syria plotting attacks against the West. The time it takes to de-conflict airspace with the Russians, when combined with the loss of on-the-ground visibility, will limit the efficacy of future airstrikes. The U.S. will cede the information space as well, enabling terrorists to communicate more freely. Jihadists will have greater freedom of action as they guide regional affiliates and direct global attacks.

ISIS will return. Although the U.S.-led coalition deprived ISIS of its territory, many of its leaders survived. Now thousands of its fighters may emerge from detention by Syrian Democratic Forces fleeing the Turkish invasion. ISIS family members, some of whom recently fled facilities deserted by Kurdish forces, are poised to repopulate any territory ISIS reclaims. The scale of the potential fighters flooding the battlefield is unprecedented in its magnitude. Most will stay in the region, but some foreign fighters will migrate home to reinforce and inspire local movements. It took three years for ISIS to form after the defeat of al Qaeda in Iraq; expect ISIS 2.0 to arise within months.

Al Qaeda may expand its stronghold in northwest Syria. The Idlib province is home to the greatest concentration of al Qaeda fighters that has existed since 9/11. Efforts by Syrian government-aligned forces to assert control have been kept at bay by Turkish and Turkish-supported Opposition forces, who will only grow stronger in the wake of the invasion. There is no force left with the will or the means to confront more than 30,000 battle-hardened jihadists who have made Idlib their home, and a sanctuary for operations.

Turkey will not fight ISIS. Turkish President Recep Tayyip Erdogan leans Islamist. He has little incentive to fight ISIS directly. He also fears an ISIS backlash inside Turkey should he act against the group. In the early years of the Syrian uprising, Turkey served as a welcome center for jihadists flocking to the fight. A number of Turkish military forces openly sympathize with jihadists. ISIS poses a greater threat to Turkey’s regional rivals, such as Iran, than it does to Turkey. The Turkish military lacks the operational reach to secure all the territory that the SDF formerly controlled. ISIS may retake terrain in the gap that exists between Turkey’s ambition and its capability. Turkey will pay a long-term price for Erdogan’s inability to balance his desire to govern a modern state with his tacit acceptance of Islamist movements.

Turkey will occupy northeastern Syria for a long time. Although many powers rhetorically oppose Turkey’s invasion of northeastern Syria, few are prepared to move beyond words. Assad’s forces cannot independently eject Turkish forces. The Kurds will have no more than limited help from Assad against the occupation. Russia values Turkey as a wedge against NATO more than it cares about Ankara’s occupation of Syria. Iran places a higher priority on building out its forward base for attacking Israel, surviving the impact of U.S. sanctions, and quelling the instability in Iraq.

The Syrian Civil War will flare up anew. Turkey’s invading forces will fight any pro-regime forces they encounter, and will continue anti-regime operations once their initial invasion is complete. The Sunni “Arab belt” that Erdogan is carving out will serve as an opposition safe haven. This new safe haven will interact with the existing al-Qaeda-dominated one in Idlib. A revived Syrian Civil War will send waves of refugees into Europe, radicalize more fighters, and destabilize neighboring countries.

The Kurds will become a regional problem. The Turkish invasion is specifically targeting the People’s Protection Units, an armed affiliate of the Kurdistan Workers Party, or PKK, which has branches in Turkey, Iraq, and Iran. Kurdish fighters across the region will have incentive to mobilize. The PKK-affiliated Kurds lost Afrin, in northwest Syria, to the last Turkish operation in Syria in early 2018. In Iraqi Kurdistan, the governing Kurdish parties lost Kirkuk – the oil-rich, disputed area in northern Iraq – to the Iraq Security Forces and Iranian proxies. Kurds of all affiliations may be incited to arm. It is an open question as to whether they will come together or work at cross-purposes, as they have done many times in their history. Perceived U.S. abandonment will trigger a rise in Kurdish militancy as they are attacked on all sides.

Iraqi protests will weaken the government and spill over into Iran. The protests in Iraq are a new phenomenon: the “Shi’a street” turning on its ruling political elite. This terrifies the leaders of Iran, who fear that the millions of Iranian pilgrims that entered Iraq to commemorate the religious observance of Arba’een may bring this idea back with them. So Tehran is sending Iranian forces to reinforce its militia groups in Iraq. Many Iranians protested against their government’s decision to deploy forces to Syria in the midst of poor economic times. They are unlikely to support the deployment of Iranian forces to Iraq. The more Iran enables a heavy-handed approach to the Iraq protests, the more it will erode support for the government it is trying to stabilize and accelerate the spillover it is trying to prevent.

Israel will take bolder action against Iran. The U.S. presence in Iraq and Syria may currently serve to moderate Israeli actions. American forces on the ground in Iraq and Syria are vulnerable to revenge attacks by Iranian-backed groups each time Israel conducts a strike. This requires Israel to take caution when attacking Iranian forces, proxies, and facilities. Iran and its proxies make no distinction between attacks conducted by Israel and those conducted by the U.S. As the U.S. withdraws from Syria, Iran will move more weapons and equipment in while Israel will strike any shipment it perceives as a threat. Israel views its more aggressive actions as necessary defensive measures. Iran will assuredly perceive them as escalatory. The more U.S. forces in Iraq and Syria draw down, the greater freedom of action Israel will perceive it has against Iran.

Russia will push the narrative of the United States as an unreliable security partner. Russian President Vladimir Putin will use the U.S. betrayal of the Kurds to cast Russia as one of the only reliable partners and mediators in the Middle East. The longitudinal effects of this information victory will not be trivial. Putin is already using the crisis to pitch his vision for “collective security” in the Gulf and the Middle East broadly. As the U.S. appears to pull back from Syria and Iraq, it affords Putin opportunities to regain ground in the Middle East and do so at a limited cost. Russia is poised to supplant the U.S. as the security partner of choice.