Gero Iwai: Army CI Agent


Gero Iwai: First Japanese American Counterintelligence Agent in the US Army

Lori S. Tagg, Command Historian, US Army Intelligence Center of Excellence

In the early morning hours of December 7, 1941, the Japanese Air Force bombed the US Naval fleet anchored in Pearl Harbor, Hawaii.  According to the multi-volume “History of the Counter Intelligence Corps” (CIC), “During the first minutes of the raid, agents of the Corps of Intelligence Police (CIP), scattered throughout the island of Oahu, raced to CIP headquarters in the Dillingham Building in downtown Honolulu. A hurried 10-minute conference and the agents were out on their first assignment of the war. Following a previously arranged plan, they dispersed in teams.  Their mission was to apprehend all pro-Japanese sympathizers.”  CIP agents began rounding up individuals on a “pickup list” compiled over the previous 10 years.  Within days, more than 400 individuals had been arrested and confined at a makeshift detention camp.  Significantly, while many of those on the list were Japanese, pre-war investigations had confirmed that allegations of espionage among the Japanese American community in Hawaii were predominantly false.

Those investigations were largely the handiwork of Gero Iwai, a 36-year-old Hawaiian native and a 10-year veteran of the CIP.  As one of the first Japanese Americans to pursue an ROTC course during his attendance at the University of Hawaii, he was appointed a 2nd Lieutenant, Infantry, in the Officers Reserve Corps upon graduation.  However, on August 19, 1931, Iwai chose to enlist in the US Army, was placed on the Detached Enlisted Men’s List (DEML), and was assigned as a CIP Investigator in the Office of the Assistant Chief of Staff (ACoS), G-2, Hawaiian Department.  [Note: the DEML was equivalent to today’s “branch immaterial” assignments.]  At the time, Iwai was the only Nisei (second generation Japanese American) employed in the G-2’s counterintelligence office.  For the first 10 years of his Army career, Iwai worked undercover, his true occupation unknown even to his own family.  He monitored the activities of the Japanese community, surveilled the activities of the Japanese Consulate General, and established a network of informants among the Japanese Americans employed at the Consulate.  Iwai and his fellow CIP agents painstakingly compiled the list of individuals they believed would be a threat to the US should war with Japan occur.


On April 8, 1941, Iwai was honorably discharged from the Army and accepted an appointment as a Reserve officer serving as the Assistant to the ACoS, G-2, Hawaiian Department.  In time, Iwai became the Officer in Charge of the Translation Section of the Counter Intelligence Detachment.  The day after the Pearl Harbor attack, given his years of experience and knowledge of the Japanese culture and language, he was the natural choice for a special joint and interagency assignment.

Iwai and fellow Nisei Douglas Wada, a Naval intelligence officer, were chosen to work with the Federal Bureau of Investigations to interrogate a captured Japanese officer.  The first Japanese prisoner of the war, Ensign Kazuo Sakamaki had commanded a Japanese midget submarine launched against targets in Pearl Harbor.  Due to mechanical issues, his submarine had run aground miles from the harbor, and he had been captured by military police.  Among Sakamaki’s possessions was a navigational chart that, upon analysis by Iwai and Wada, was found to designate the berthing locations of all the major carriers and warships of the US Navy.  Furthermore, documents recovered from the Japanese Consulate and translated by Iwai and Wada provided further evidence of the staggering extent of Japanese pre-war espionage.

Throughout the war, Iwai continued to conduct counterintelligence work for the Counter Intelligence Corps (CIC), successor to the CIP.  His personal crusade was to prove the Japanese Americans in Hawaii were loyal to the US.  His thorough investigation uncovered not a single subversive or hostile act against the US on the part of Japanese Americans.  His top-secret report to that effect reportedly swayed the opinions of military leaders, including Gen. Delos C. Emmons, commander of the US Army in Hawaii, who subsequently proposed the formation of what would become the 100th Infantry Battalion, made up almost entirely of Japanese Americans from Hawaii.

Iwai remained in Honolulu with the 401st CIC Detachment until 1949, when he was assigned to the 441st CIC Detachment in Tokyo. He returned to the US in 1954 and, after 26 years of honorable service, retired from military service as a Lieutenant Colonel in 1957.  Ironically, Iwai’s efforts to prove the loyalty of the Hawaiian Japanese Americans both before and during World War II had completely estranged him and his family from the community he sought to protect.  Instead of living his final years in his beloved native Hawaii, Iwai settled in San Francisco, where he passed away in 1972.

Caption:  Lt. Col. Gero Iwai, the US Army’s first Japanese American counterintelligence agent, was posthumously inducted into the Military Intelligence Hall of Fame in 1995.





0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply