DAMASCUS, Jan 22 (Reuters) - A U.S. envoy called for a truce between the Syrian government and Kurdish-led forces to be upheld, urging steps to build trust after Damascus captured swathes of the northeast in a push to reassert central authority.

President Trump’s bet on Syria’s new leader is facing a pivotal moment, as Kurdish forces are under attack from President Ahmed al-Sharaa’s forces in the northeast and facing growing pressure to fold into the central government.

The Kurdish-led Syrian Democratic Forces have fallen from power in Syria as the U.S. shifts its backing to the country's new leaders in Damascus

The rapid turn of events has brought almost all of Syria back under the authority of the central Damascus-based state following years of civil war that fractured the country, and puts a spotlight on shifting U.S. policy. The Reuters Gulf Currents newsletter brings you the latest on geopolitics, energy and finance in the region. Sign up here.

The Syrian government's attempt to wrest back control of Kurdish-held areas has thrown into doubt the fate of thousands of suspected Islamic State group jihadists detained there, with Western observers worried many could take advantage of the chaos to escape.

However, the SDF was led by the main Kurdish fighting force in Syria, the People’s Protection Units, known as the YPG. The dominant role of Kurdish fighters in the alliance remained a concern for the majority Sunni Arab factions and their regional backers, and internal clashes broke out on several occasions.

ANKARA, Jan 21 (Reuters) - Turkish President Tayyip Erdogan said on Wednesday that Kurdish forces in northern Syria must lay down weapons and disband now to avoid further bloodshed, after Damascus struck a ceasefire with the group and gave them four days to agree on integrating into the central state.

"We've requested and demanded guarantees, but as always, the U.S. does not give any," the SDF's political co-chair told Newsweek.

Deir al-Zour has been described as the most heavily damaged city in Syria by U.N.-Habitat. Traffic weaves past craters and around mounds of rubble. Children play in the ruins beneath great slabs of concrete hanging perilously from buildings. Dust clogs the air.

DAMASCUS, Jan 21 (Reuters) - Syria's government accused the Kurdish-led Syrian Democratic Forces of attacks it said killed 11 soldiers on Wednesday, but the SDF disputed key elements of the account, blaming at least one deadly blast on explosives being moved by Syrian troops.