President-elect Donald Trump is threatening to impose sweeping new tariffs on Mexico, Canada and China as soon as he takes office as part of his efforts to crack down on illegal immigration and drugs.

"On January 20th, as one of my many first Executive Orders, I will sign all necessary documents to charge Mexico and Canada a 25% Tariff on ALL products coming into the United States, and its ridiculous Open Borders," he wrote on social media, complaining that "thousands of people are pouring through Mexico and Canada, bringing Crime and Drugs at levels never seen before," even though violent crime is down from pandemic highs.

He said the new tariffs would remain in place "until such time as Drugs, in particular Fentanyl, and all Illegal Aliens stop this Invasion of our Country! "

The tariffs, if implemented, could dramatically raise prices on everything from gas to automobiles. The U.S. is the largest importer of goods in the world, with Mexico, China and Canada its top three suppliers, according to the most recent Census data.

Trump made the announcements on his Truth Social site Monday evening as he railed against an influx of illegal migrants. 

CBS News also reported Monday that unlawful crossings at the U.S.-Mexico border are on track to drop to a new low for the Biden administration in November, according to internal Customs and Border Protection figures.

U.S. Border Patrol is on pace to record fewer than 50,000 apprehensions of migrants crossing the southern border unlawfully this month. 

Trump also turned his ire on China, saying he has "had many talks with China about the massive amounts of drugs, in particular Fentanyl, being sent into the United States – But to no avail."

"Until such time as they stop, we will be charging China an additional 10% Tariff, above any additional Tariffs, on all of their many products coming into the United States of America," he wrote.

It is unclear whether Trump will actually go through with the threats or if he is using them as a negotiating tactic before he takes office in the new year.

Much of America's fentanyl is smuggled from Mexico. Border seizures of the drug rose sharply under President Joe Biden, and U.S. officials tallied about 21,900 pounds (12,247 kilograms) of fentanyl seized in the 2024 government budget year, compared with 2,545 pounds (1,154 kilograms) in 2019, when Trump was president.

Trump's nominee for treasury secretary, Scott Bessent, if confirmed, would be one of several officials responsible for imposing tariffs on other nations. He has on several occasions said tariffs are a means of negotiation with other countries.

He wrote in a Fox News op-ed last week, before his nomination, that tariffs are "a useful tool for achieving the president's foreign policy objectives. Whether it is getting allies to spend more on their own defense, opening foreign markets to U.S. exports, securing cooperation on ending illegal immigration and interdicting fentanyl trafficking, or deterring military aggression, tariffs can play a central role."

If Trump were to move forward with the threatened tariffs, the new taxes would pose an enormous challenge for the economies of Canada and Mexico, in particular.

They would also throw into doubt the reliability of the 2020 trade deal brokered in large part by Trump, which is up for review in 2026.