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.





COL Lansdale, CIC

CIC Detachment Ensures Success of the Manhattan Project

CIC Detachment Ensures Success of the Manhattan Project

Lori S. Tagg,  USAICoE Command Historian

The United States program to develop the atomic bomb, codenamed the Manhattan Project, began in August 1942.  From the beginning, the need for security was paramount.  The project had to be protected from sabotage and espionage and, equally important, the fact that the US was working on such a program had to be kept under wraps at all cost.  Early on, a Protective Security Section (PSS) handled personnel and information security, facility protection, and security education.

By February 1943, a more comprehensive counterintelligence program was warranted and Counter Intelligence Corps (CIC) agents Capt. Horace K. Calvert and Capt. Robert J. McLeod were assigned to the Manhattan Engineer District (MED) to organize the Intelligence Section.  More CIC personnel followed, with agents stationed at Oak Ridge, Tennessee; Chicago; St. Louis; Site Y (Los Alamos, New Mexico); and Berkeley, California.  By August 1943, when the project transferred to the Corps of Engineers, the Intelligence Section merged with the PSS and established its headquarters at Oak Ridge.  At this time, the Section assumed responsibility for every aspect of security within the MED.  Four months later, on December 18, 1943, a special CIC Detachment, commanded by Lt. Col. William B. Parsons, was organized, and Lt. Col. John Lansdale became the chief of intelligence and security for the entire Manhattan Project.

In the early 1940s, Lansdale, a graduate of the Virginia Military Institute (VMI) and a US Army Reserve officer, was a successful trial lawyer in Cleveland, Ohio.  He had turned down several calls for active duty before finally taking the advice of one of his VMI classmates to accept special duty within the War Department’s Military Intelligence Division (MID). Lansdale initially worked in the Investigation Branch, Counter Intelligence Group, reviewing investigative reports of prospective War Department employees.  He eventually became chief of both the Investigation and Review branches of MID.  Another one of his duties was to act as liaison between the PSS and the Assistant Chief of Staff, Intelligence.  When the Manhattan Project transferred to the Corps of Engineers and the CIC Detachment activated, Lansdale had the background and connections to move effortlessly into the position as head of intelligence and security.  Due to the criticality of his mission, Lansdale quickly became special assistant to Gen. Leslie Groves, the chief of the MED.

The CIC Detachment was initially comprised of 25 officers and 137 enlisted agents, each one hand-picked by Captains Calvert and McLeod.  Over the next year, the Detachment grew to 148 officers and 161 enlisted agents.  This included non-CIC military personnel with specific technical abilities critical to the security of the program.  Detachment Headquarters was centralized at Oak Ridge, but personnel were placed on detached service in 11 branch offices around the nation.  At times, these agents were so highly classified that they were referred to by code symbols and only the Finance Officer computing the pay of the agent knew his exact location.

Lansdale assumed full responsibility for all intelligence and security matters affecting the MED.  In addition to preventing unintentional disclosure of information and infiltration by enemy agents, Lansdale’s responsibilities included preventing fires and explosions, monitoring courier duties, protecting classified shipments, educating personnel about the importance of security measures, obtaining newspaper cooperation, and conducting 400,000 background investigations of potential personnel.  His agents acted as bodyguards for the project’s top scientists and went undercover to monitor local rumors about the various installations involved in the bomb development.  Lansdale also planned and executed the security measures for the 509th Composite Group, the special Army Air Forces’ organization formed to deliver the bombs.  Additionally, he was deeply involved in the Alsos Mission, an overseas task force that seized the technology and scientists involved in German atomic research.

The dropping of the atomic bomb on Hiroshima and Nagasaki, Japan brought about the end of World War II and saved the lives of thousands of US and Allied troops who would have died in an invasion of Japan.  The procedures put in place by Lansdale and his CIC Detachment led to the successful protection of the atomic bomb program, later called the “War’s Best Kept Secret.”

COL Lansdale, CIC

Colonel John Lansdale, Jr., was a civilian lawyer and Army reservist who requested a call to active duty with the War Department’s Military Intelligence Division. He served as the head of Intelligence and Security for the Manhattan Project from 1941 to 1946.

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