President Donald Trump on Saturday authorized the deployment of troops in the northwestern US city of Portland and at Immigration and Customs Enforcement (ICE) facilities, extending his contentious domestic use of the military.

"At the request of Secretary of Homeland Security, Kristi Noem, I am directing Secretary of War, Pete Hegseth, to provide all necessary Troops to protect War ravaged Portland, and any of our ICE Facilities under siege from attack by Antifa, and other domestic terrorists," Trump wrote on his Truth Social platform.

"I am also authorizing Full Force, if necessary," he added, without specifying what "full force" meant.

This is the latest in a series of controversial decisions in which Trump has deployed or threatened to send the US army to act against its own citizens, amid local protests.