Why might Vietnam be wary of outside influence/foreigners?

Because Vietnam was previously occupied by the French and then invaded by the United States.

Explanation:

the pogroms became known as kristallnacht, the "night of shattered glass," for the shattered glass from the store windows that littered the streets. the morning after the pogroms 30,000 german jewish men were arrested for the "crime" of being jewish and sent to concentration camps, where hundreds of them perished.