Forces loyal to Syrian President Bashar al-Assad advanced Monday into several key towns across northeastern Syria after an 11th-hour deal with local Kurdish fighters, dramatically altering the balance of power inside the war-battered country.

Under the deal, which aimed to forestall a Turkish assault against the Kurds, Syrian government forces arrived in the towns of Tabqa, on the outskirts of Raqqa, and Ain Issa, which served as the headquarters of the Kurdish-led autonomous administration in northeast Syria, about 20 miles from the Turkish border. Images published by the official Syrian Arab News Agency showed government troops arriving atop pickup trucks and waving Syrian flags…

As the violence has spiked, aid agencies have been scaling back or suspending humanitarian operations because of shelling, road closures and other threats. All international aid groups have now withdrawn their personnel, according to the Kurdish Red Crescent.

“This is our nightmare scenario. There are tens of thousands of people on the run, and we have no way of getting to them,” said Made Ferguson, deputy country director for Syria at Mercy Corps, a U.S.-based aid agency. “The humanitarian crisis is worsening by the day, and now aid workers are cut off from providing lifesaving assistance to the most vulnerable.”