The International Crisis Group warned that ISIS could stage a comeback amid the new conflict that has erupted in Syria in the wake of US President Donald Trump ordering a withdrawal of troops from some areas. Turkey’s intervention and spillover from US-Iran tensions a very real concern the report argues.The Turkish operation targeting the Syrian Democratic Forces, which until just a week ago were a key partner of the US war on ISIS, will force them to concentrate on defending against withering bombing and artillery attacks by Turkey and the presence of Turkey’s proxies, a force of Arab fighters Turkey recruited from other parts of Syria and rebranded as a Syrian “National army.” ISIS could exploit the situation the Crisis Group warns.Syria is not a vacuum and when ISIS makes progress in Syria it will affect Iraq. “ISIS continues its guerilla insurgency in rural areas,” the report notes. It concludes that the US and allies “should work to convince Turkey to limit its incursion.” The US has been of two-minds on that, both warning Turkey but also opening the airspace for airstrikes. Artillery bombardment from Turkey came dangerously close to US soldiers in Kobani, showing how the US opening the border to the Turkish attack has paved the way for threats to America’s own.Titled “averting an ISIS resurgence in Iraq and Syria,” the report includes reactions from Crisis Group experts. “It's one thing to want to reduce the United States' military involvement in the Middle East. It's another thing entirely to have done so without any preparation, heedless of consequence, back-stabbing the Kurdish forces after having discouraged them from reaching a deal with the Syrian regime, openly inviting a Turkish intervention, and potentially giving ISIS another lease on life. Unfortunately, that is what is happening, and the predictable implications are clear for all to see,” Robert Malley, the President and CEO of Crisis Group, says. Similarly Sam Heller, a Senior Analyist for Non-state Armed Groups at the group notes that “Turkey's newly launched intervention into Syria's north east will draw the SDF into a fight for its survival, short-circuiting ongoing counter-ISIS efforts. That could allow ISIS to regroup in Syria, and potentially destabilise neighbouring Iraq.In short, bad news. The October 6 decision by Trump caught US allies by surprise, left US partners on the ground surprised and feeling betrayed and has also left US commanders and officials shocked. Up until the announcement the official policy of the US was to train up to 110,000 members of the SDF and stabilize eastern Syria. Then the US decided to open the airspace so Turkey could bomb the very same SDF the US was training, in the process killing civilians and causing up to 100,000 people to flee an area of Syria that had been peaceful for many years. The US opened the gates to the destruction of cities and towns across eastern Syria, a once stable area that was recovering from the ISIS conflict.The Crisis Group conducted 150 interviews and carried out field research to create its latest, timely report. The report concentrates heavily on Iraq, noting that the coalition has been assisting Iraq to help fight ISIS but may not remain forever. It notes that “Iraq faces the challenge of securing its periphery, including areas like rural Ninewa and Kirkuk’s Hawija countryside.” This is an area where there is ISIS presence. In addition in Mosul the city still lacks key infrastructure more than two years after ISIS was defeated. Crisis Group calls this “post-war dysfunction.”Turkey’s invasion of Syria now risks spreading chaos again across Syria and Iraq. This could “endanger Iraq’s stability all over again, ISIS is already most active in eastern expanses of Syria that are tightly linked, geographically and historically, to the organizations area of operation across the frontier.”Trump chose to suddenly leave parts of Syria because he wants other countries to pay to secure Syria and not have the US lead the way. However, with just 50 soldiers and a few observations points the US has kept the peace in an area of Syria the size of Israel.Like many reports the Crisis Group looks primarily at how this can empower ISIS or lead the SDF to negotiate with the Syrian regime via discussions with Russia. Larger questions remain about the harm done to the fabric of civilian life in eastern Syria, long-term harm that already has ramifications across Syria and Iraq. ISIS is one beneficiary.