U.S. Secretary of State Marco Rubio visited the Panama Canal on February 2, warning the host country that Washington will “take measures necessary” if it doesn’t curb Chinese involvement in the crucial waterway.

Following the threats, Panamanian President Jose Raul Mulino seemed to take that to heart as he said he addressed Washington’s concerns over Beijing’s purported influence by not renewing Panama’s deal to join China’s flagship Belt and Road Initiative (BRI).

Mulino also announced further steps to cooperate on immigration, a major policy matter with the U.S. administration.

The decision to not renew the 2017 memorandum of understanding to join the BRI marks an early move to calm Washington’s concerns over Chinese influence in Panama. The BRI is Chinese leader Xi Jinping’s signature foreign policy initiative, and the globe-spanning infrastructure project has led to hundreds of billions of dollars worth of Chinese investment around the world.

State Department spokeswoman Tammy Bruce said Rubio delivered a message from President Donald Trump stating that China’s presence was a threat to the waterway and a violation of the U.S.-Panama treaty.

“Secretary Rubio made clear that this status quo is unacceptable and that absent immediate changes, it would require the United States to take measures necessary to protect its rights under the treaty,” Bruce said.

Rubio did not specify the steps Panama needed to take or suggest what moves the United States might take in retaliation if measures were not taken.

Mulino told reporters that Panama will seek to work with the United States on new investments, including infrastructure projects.

“I think this visit opens the door to build new relations…and try to increase as much as possible U.S. investments in Panama,” he said.

Trump has said he does not rule out military force over Panama — remarks that irked many U.S. allies in Latin America and elsewhere.

In comments on February 2, Trump claimed that “China’s running the Panama Canal.”

“That was not given to China, that was given to Panama — foolishly — but they violated the agreement, and we’re going to take it back, or something very powerful is going to happen,” Trump told reporters.

Trump has also made remarks about the United States potentially purchasing the island of Greenland from Denmark — which says it’s not for sale — and suggested Canada should annex itself to the United States, although the seriousness of those comments was not clear.

China’s business with the canal is mainly carried out through Hong-Kong based Hutchison Holdings, which operates two ports near the entrances to the waterway under a 25-year concession renewed in 2021.

Rubio last week said that under the current status, China could theoretically use the ports to shut down the canal should a conflict break out between the United States and the Asian giant.

The Panamanian president said his meeting with Rubio was cordial and respectful. He indicated it was possible to review some Chinese businesses in Panama, including the port concession.