China said on Monday it is willing to repatriate confirmed Chinese nationals from the United States, as U.S. President Donald Trump has threatened tariffs and sanctions on some countries if they do not cooperate on accepting deportees.

In recent months, U.S. Immigration and Customs Enforcement (ICE) has sent five charter flights, opens new tab to China with hundreds of Chinese nationals deemed to not have a legal basis to remain in the U.S.

Nonetheless, U.S. Department of Homeland Security officials have been frustrated by what they say is Beijing's longstanding refusal to cooperate on repatriation by declining to issue travel documents.

The department has warned of escalating consequences for Chinese officials, including visa sanctions, for refusal to accept tens of thousands of Chinese nationals, opens new tab in the U.S. under deportation orders.

"We have conducted practical cooperation with the migration and law enforcement departments of the U.S. and other countries, which has been productive," Chinese Foreign Ministry spokeswoman Mao Ning told reporters at a regular briefing in Beijing.

"As far as repatriation is concerned, China's principle is to receive the repatriates who are confirmed as Chinese nationals from the Chinese mainland after verification," Mao said when asked if China would take back Chinese nationals who are in the U.S. illegally or without documentation.

Trump in his first day in office last week declared illegal immigration a national emergency, tasking the U.S. military with aiding border security, issuing a broad ban on asylum, and taking steps to restrict citizenship for children born on American soil.

The Republican president says the moves are necessary after millions of immigrants entered the U.S. under the Biden administration, both crossing illegally and through Biden's legal entry programs.

The number of Chinese citizens encountered crossing the U.S. southern border without permission surged in recent years, from negligible to tens of thousands, as China's economy faced headwinds and U.S. visas were harder to acquire due to COVID-19 restrictions.

Trump had threatened tariffs and sanctions on Colombia to punish it for earlier refusing to accept military flights carrying deportees. The White House said on Sunday it would not impose its threatened penalties because the country had agreed to accept the migrants.

Trump also has said he is thinking about imposing 25% duties on imports from Canada and Mexico on Feb. 1 to force further action against illegal immigration and fentanyl flowing into the U.S.