BEIJING (AP) — The top U.S. and Chinese trade envoys have spoken by phone in their first known contact since Presidents Donald Trump and Xi Jinping agreed to resume stalled talks on ending a tariff war.

Beijing's envoy, Vice Premier Liu He, talked Tuesday with Trade Representative Robert Lighthizer and Treasury Secretary Steven Mnuchin, the Commerce Ministry said. Its one-sentence statement gave no details or timeline for more contacts.

Last month's agreement by Trump and Xi following a meeting in Japan helped to steady jittery financial markets. But economists warn it might be fragile because the same disagreements that caused talks to stall in May remain.

Both sides have raised tariffs on billions of dollars of each other's goods in the dispute over U.S. complaints about Beijing's technology ambitions and trade surplus.

Washington is pressing Beijing to roll back industry plans its trading partners say violate its free-trade commitments and are based on stealing or pressuring foreign companies to hand over technology.

Beijing has offered to narrow its trade surplus by purchasing more American exports. But it has balked at discarding industry plans communist leaders see as the path to prosperity and global influence.