BEIJING — China signaled on Thursday that it might continue to weaken its currency, a move that threatens to again escalate the trade war with the United States.

China’s central bank set the midpoint of the renminbi’s daily trading range above 7 to the American dollar for the first time in more than a decade. Thursday’s move in effect tells financial markets that Beijing expects the renminbi to continue to weaken versus the dollar, perhaps well past the 7-to-the-dollar level.

That is likely to provoke more ire from the Trump administration. A weaker currency helps Chinese factories offset the higher costs of Mr. Trump’s tariffs when selling their goods to the United States.

The move by the People’s Bank of China in itself will not change the economics of the Chinese-American trade relationship. China on Thursday set the currency’s midpoint at 7.0039 to the dollar, compared with the 6.9996 point it set on Wednesday. China tightly controls trading of its currency, with that midpoint determining the center of a narrow range in which the renminbi can strengthen or weaken during the day.