Senator Steve Daines said in an interview that in meetings with Chinese officials, he called for talks between President Trump and China’s leader, Xi Jinping.

Progress on battling fentanyl trafficking could be lost, and so could American lives.

The decrease in fentanyl overdoses, drug policy experts have said, has more to do with public health measures than changes in border policies.

China is still cautiously trying to figure out what Trump wants. The president has threatened big tariffs in response to the inaction.

Aiming to appease President Trump, Mexico is hitting China with tariffs, handing cartel leaders over to the United States and using C.I.A. intelligence to hunt down others.