You’re right. In the reading I’ve done on WW2 one of the recurring themes is American soldiers meeting Japanese soldiers who went to school in the US, who grew up in the US, played baseball, and etc.
When these Japanese-Americans had to choose between the US and Japan they chose Japan.
Thus there was good reason to be cautious about a population within our borders who were known and proven to have had loyalties to and sympathies with the enemy.
Not unlike today with the Muslims who lobby for Sharia law in the USA. They’re our enemies, too.
The religion of the Japanese then was Shinto-Budism, a religion that holds the the Emperor of Japan to be a God - who required absolute allegiance and obedience. Today's PC media and education institutions censor the fact that most Japanese homes had a small Shinto-Budist shrine/alter where the family would pray and declare devotion to the Emperor.
That's the unavoidable reason why yesterday's equivalent of Islam's suicide bombers were Japan's Kamikazes.
You’re right “Martial” and not “Marshal”... Unless Marshal Dillon was enforcing it.