The tariffs on Mexico and Canada will remain in place until the two countries clamp down on drugs, particularly fentanyl, and migrants illegally crossing the border, Trump said in a post on his Truth Social platform.
“Both Mexico and Canada have the absolute right and power to easily solve this long simmering problem,” he said.
“It is time for them to pay a very big price!”
In a separate post, Trump attacked Beijing for failing to follow through on promises he said Chinese officials made to carry out the death penalty for people caught dealing fentanyl.
A spokesperson for the Chinese embassy in Washington told the BBC “the idea of China knowingly allowing fentanyl precursors to flow into the United States runs completely counter to facts and reality”.
“China believes that China-US economic and trade cooperation is mutually beneficial in nature. No one will win a trade war or a tariff war,” he added.
During his election campaign, Trump said he would impose tariffs of more than 60% on all Chinese-made products, much higher than those he put in place during his first term in office.
Trump has also said he will end China’s most-favoured-nation trading status with the US – the most advantageous terms Washington offers on tariffs and other restrictions.
It comes as the Chinese economy is in a significantly more vulnerable position than it was during the previous Trump presidency.
The country has been struggling with a number of serious issues, including an ongoing property market crisis, weak domestic demand and growing local government debt.
BBC News has contacted the foreign ministries of Mexico and Canada for comment.