Secretary of State Marco Rubio said on Thursday he had "zero doubt" that China has a contingency plan to shut down the Panama Canal in the event of a conflict with the U.S. and that Washington intends to address what it sees as a national security threat.

Rubio said he could not predict if Trump would succeed in buying Greenland from Denmark or restoring American authority over the Panama Canal while he is in office.

The top US diplomat said President Donald Trump’s proposal to buy Greenland “is not a joke” because of the risk that China would station resources on the island that threaten American security and the importance of Arctic shipping lanes for energy exports.

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.

China's veteran foreign minister has issued a veiled warning to America's new secretary of state: Behave yourself.Foreign Minister Wang Yi conveyed the message in a phone call Friday, their first conversation since Marco Rubio's confirmation as President Donald Trump's top diplomat four days earlier.

A key focus of Secretary of State Marco Rubio’s visit to Central America this week — his first trip as America’s top diplomat — will be to counter China’s growing influence in the region, the State Department’s top spokesperson said this week,

Secretary of State Marco Rubio states Trump's interest in Greenland and the Panama Canal is driven by national security concerns regarding China.