He was arrested by the FBI on suspicion of espionage in the lead-up to World War II, and he was held in an internment camp, before being released in 1949 and returning to Japan in the 1950s.

Kono has been the subject of increasing historical interest, both for the insights that his papers have provided into Chaplin's complicated relationship with Japan, and because he was one of the few Asian residents of the United States to be active in the nascent American film industry.

[3] Kono provided one of the few firsthand accounts of the events leading up to the mysterious death of Thomas Ince in 1924.

[5] Because the political situation in Japan was extremely volatile, Kono has been credited with helping Charlie and Sydney Chaplin to travel more safely through the country.

[3] Before the attack on Pearl Harbor, Kono was arrested by the FBI for alleged social connections to Japanese spies.

[3][4] The Japanese military strike on Pearl Harbor occurred while the United States was attempting to deport Kono to Japan, at which point he was relocated to the Kooskia Internment Camp.