WASHINGTON—President Trump hit back hard against China but left the door open for talks to lower tariffs on other countries, trade-war moves that left much of the world confused as countries raced to avoid damaging new duties on their goods.

While Trump and many White House advisers continued to suggest there would be no quick end to new import duties, the president also fueled optimism that deals with individual coun

The future of the popular video app is now at the center of a geopolitical tussle between Washington and Beijing.