President Donald Trump has threatened to releases hundreds of Islamic State fighters captured by the United States in Syria if Britain, Germany and other European countries did not take back their nationals among them, and put them on trial.

The alternative, he warned is not good. “The U.S. does not want to watch as these ISIS fighters permeate Europe, which is where they are expected to go.”The president announced last December the IS had been decimated and that he was pulling out the 2,000 US troops deployed to combat the terrorist organization in Syria.

The sprawling IS caliphate, that had once included vast swatches of territory in Syria and Iraq, has shrunk to a tiny encampment in the village of Baghouz on the eastern banks of the Euphrates river, Kurdish-led Syrian Democratic Forces said on Saturday.

Differences persist among his official though on the extent of the damage inflicted on the IS. Secretary of defense James Mattis quit in protest against US exit, and the Pentagon and the US intelligence community have also said that though they agree the Islamic State has been diminished significantly the war is no over. And that they could be lying low for now and may re-emerge after the US troops had left.

President Trump has said a complete victory is at hand. ““It should be formally announced sometime probably next week that we will have 100 percent of the caliphate,” the president said in an address to diplomats and officials of the 30 countries that form the “Global Coalition to defeat ISIS”, recently.

The American president’s threat to release the captured IS fighters comes amidst a debate taking place in European countries on what to with them. Some countries, such as France, have announced they will take back their nationals.