US President Donald Trump said Monday that he would double tariffs on Canadian vehicles beginning in 2027, as the neighboring countries spiral towards an escalating trade war.

"On January First, 2027, Tariffs on all Cars, Trucks, both large and small, Automotive Parts, and Steel, will be increased to 50%," he wrote on his Truth Social platform.

The current US tariff on autos stands at 25 percent for non-US content, while imported steel to the United States generally faces a 50-percent duty.

Trump's latest threat comes after the North American neighbors failed Friday to reach a deal to avert new 50-percent tariffs imposed by the Trump administration on select Canadian goods.

The White House had alleged "discriminatory treatment" by Canada against US alcohol, automobile and dairy products in rolling out the duties.

Trump delayed their implementation by three days last week as Washington and Ottawa stepped up negotiations towards a trade pact.

However, the steep duties took effect Saturday as both sides failed to reach an agreement, and it hits about 5.5 percent of Canadian goods entering the United States, or some $20 billion worth of products ranging from hockey sticks to cement.

Canadian Prime Minister Mark Carney has since announced retaliatory tariffs on the United States after walking away from what he called a "bad deal."