As early as Friday, President Donald Trump is expected to invoke the Alien Enemies Act — a wartime law that allows the president to detain or deport the natives and citizens of an enemy nation — as part of the efforts to carry out mass deportations, according to two U.S. officials familiar with the matter.

The Department of Defense is not expected to have a role in the invoking of the authority, which could be used to deport some migrants without a hearing.

There have been discussions inside the administration about invoking the act, multiple sources said.

Trump had previously said on the campaign trail that he planned to invoke the act.

The act hasn’t been used since World War II, when it was used to detain Japanese Americans.

During World War II, the Alien Enemies Act was partially used to justify the internment of Japanese immigrants who had not become U.S. citizens. The broader internment of Japanese-Americans was carried out under executive orders signed by President Franklin D. Roosevelt and not the Alien Enemies Act since the law does not apply to U.S. citizens.