U.S. President Donald Trump has hailed the defeat of Daesh fighters in their self-proclaimed capital of Raqqa as a critical breakthrough in a worldwide campaign against the militants.

In a statement, he said the U.S. Campaign against Daesh would soon enter a new phase, in which the United States would support local security forces, de-escalate violence across Syria.

Earlier, Kurdish-dominated Syrian democratic forces had formally announced y Raqqa’s liberation from Daesh after four months of battles and said the city would be part of a decentralized federal Syria.