Qamishli
© The IndependentFires rage in the northern Syrian town of Qamishli city following Turkey's military incursion
On Thursday a car bomb detonated in the town of Tal Abyad, wounding several Turkish-backed Syrian fighters outside their militia headquarters, following at least three other similar blasts this week, which targeted various groups fighting in northeast Syria.

The AP reports "There was no immediate claim of responsibility for the bombing" and confirmed that "Similar bombings have taken place in the past in another enclave held for several years by Turkey and its Syrian allies on the northwest part of the border." Multiple civilian casualties have been reported in each case.

This sudden spate of mystery bomb attacks in heavily trafficked civilian areas suggests a resurgent ISIS could already be at work, after this month's Turkish invasion of Syrian Kurdish areas has resulted in mass ISIS prison breaks in the region.

On Wednesday President Trump's Special Representative for Syria Engagement, James Jeffrey, revealed in Congressional testimony that over 100 Islamic State terrorists previously held in Kurdish prisons are now on the loose.

Defense Secretary Mark Esper also confirmed the number in a CNN interview, but tried to downplay it as less than expected.

Russian figures, meanwhile, have been much higher, with Russian Defense Minister Sergei Shoigu saying on Tuesday that "Moscow estimated that up to 500 people, including Islamist fighters, had escaped from captivity in northern Syria after their guards left their posts."

Russia's defense ministry has said measures were being taken for Russian and Syrian forces to capture ISIS prisoners which are on the loose, which could require additional Russian troops reinforcements, according to the statement.

Given the latest bombings seem to have targeted various players — all rivals and/or enemies of ISIS — including pro-Assad forces, the SDF, and some among the Turkish backed 'rebel' groups, it's likely that 'underground' ISIS cells and recent escapees are attempting to take advantage of the chaos.

Multiple reports have detailed large-scale ISIS and Islamist prison breaks since the start of Turkey's 'Operation Peace Spring' on Oct. 9.Estimates put the total number of detained ISIS members in northeast Syria still under Kurdish supervision at 10,000.