What is the Alien Enemies Act, meant for wartime, that Trump is expected to invoke for mass deportations?

President Donald Trump is expected to invoke the Alien Enemies Act, reports said to give an impetus to his mass deportation programs. The Act is a wartime law that allows the president to decide to deport immigrants from an enemy nation. During his campaign, Trump said that he planned to invoke the Acy which has not 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.
The other two occasions the Act was invoked were also during war.
The law is designed to be invoked if the US is at war with another country, or a foreign nation has invaded the US or threatened to do so. Legal experts say it would be difficult for Trump to use the act when the US isn’t being attacked by a foreign government, even if the administration does cite threats from gangs or cartels.
The primary target of the law would be Tren de Aragua, the Venezuelan organized crime group that has become active in the US. Trump earlier ordered his administration to designate Tren as a terrorist organization. Once enacted, the law will help the mass deportation programs too, experts said.
The Act requires the president to declare the event that prompted the Act to be invoked. And it will remain in effect until the president terminates it.
On January 20, Trump ordered his administration to prepare for the implementation of the Act is he decided that foreign drug cartels qualified as an “invasion” or “predatory incursion” for invoking the Act.