Frustrated that China has not done more to rein in North Korea, the Trump administration could impose new sanctions on small Chinese banks and other firms doing business with Pyongyang within weeks, two senior U.S. officials said.

The U.S. measures would initially hit Chinese entities considered "low-hanging fruit," including smaller financial institutions and "shell" companies linked to North Korea's nuclear and missile programs, said one of the officials, while declining to name the targets.

It would leave larger Chinese banks untouched for now, the official said.