WASHINGTON (AP) -- Secretary of State Marco Rubio says President Donald Trump's desire to acquire Greenland and retake control of the Panama Canal is driven by legitimate national security interests stemming from growing concerns about Chinese activity and influence in the Arctic and in Latin America.

Ahead of a trip to Central America that will start in Panama this weekend, Rubio said Thursday that he could not predict if Trump would succeed in buying Greenland from Denmark or restoring American authority over the Panama Canal while he is office. But he said the attention that Trump will give to both would have an impact.

"What I think you can rest assured of is that four years from now, our interest in the Arctic will be more secure; our interest in the Panama Canal will be more secure," Rubio said in an interview with SiriusXM host Megyn Kelly.

Rubio will arrive in Panama on Saturday on his first official foreign trip as America's top diplomat, signaling the importance that both he and Trump place on securing the canal. Although immigration will be a major topic of conversation in Panama and at his other stops, Rubio said the canal issue is a priority.

Chinese investments in ports and other infrastructure and facilities at both the Pacific and Caribbean ends of the canal are a cause for major concern, leaving Panama and the critical shipping route vulnerable to China, he said.

"They're all over Panama," Rubio said of Chinese companies that many experts believe are beholden to the government in Beijing and would carry out orders to cut off or limit traffic to the canal in the event of a conflict with Taiwan or an unrelated breakdown in relations with the U.S.

"If the government in China in a conflict tells them to shut down the Panama Canal, they will have to," he said. "I have zero doubt that they have contingency planning to do so that is a direct threat."

Rubio added that "if China wanted to obstruct traffic in the Panama Canal, they could" and that would be a violation of the 1977 treaty signed by former President Jimmy Carter under which the U.S. ceded control of the American-built canal to Panama in 1999.

He also echoed Trump's complaint that American ships are being overcharged for using the canal, which would also be a violation of the treaty.

"We should not be in a position of having to pay more than other countries. In fact, we should be getting a discount or maybe for free, because we paid for the thing," he said.

Earlier Thursday, Panamanian President Jose Raul Mulino said there will be no negotiation with the United States over ownership of the Panama Canal and that he hoped Rubio's visit would instead focus on shared interests like migration and combating drug trafficking.

"It's impossible, I can't negotiate," Mulino said when asked about returning the canal to U.S. control. "That is done. The canal belongs to Panama."

But Rubio said it would be discussed.

"We're going to address that topic," he said. "The president's been pretty clear he wants to administer the canal again. Obviously, the Panamanians are not big fans of that idea. That message has been brought very clear."

On Greenland, he said Denmark, of which Greenland is a part, did not have the capability to defend Greenland from China as it seeks to gain a presence in the Arctic to exploit shipping routes.

And since Greenland is already covered by the NATO mutual defense pact due to its relationship with Denmark, it made sense for the U.S. to have a greater presence and authority there.

"If we're already on the hook for having to do that, we might as well have more control over what happens there. I know it's a delicate topic for Denmark, but it's again a national interest item for the United States," Rubio said.