Uanna was in charge of security at the project's facility at Oak Ridge, Tennessee, and later at the 509th Composite Group, which dropped atomic bombs on Hiroshima and Nagasaki.

With 112 officers and 35 agents he conducted investigations and evaluated the loyalty of individuals within X Corps and trained its troops in security procedures.

[9][10] Joining the Manhattan Project in late 1943, Uanna was initially assigned to the New England area, where he looked after security at 150 organizations, including key contractors Stone & Webster, General Electric, Westinghouse and American Cyanamid, and universities such as Harvard, Brown, Yale and MIT.

In August 1944, he was appointed Security Officer for the large town and industrial installation built by the US Government at Oak Ridge, Tennessee, to enrich uranium for an atomic bomb.

He supervised the activities of the town's police, detectives and welfare bureau and provided security for the transport of fissile materials from Oak Ridge to the weapons laboratory at Los Alamos, New Mexico.

[9][10] In February 1945, Uanna assumed command of the 1st Technical Service Detachment, which was attached to the 509th Composite Group,[10] the Army Air Force unit created to deliver the first atomic bomb.

Uanna arrived with orders from Lieutenant Colonel John Lansdale Jr.,[11] the Manhattan Project's head of security,[12] and a briefcase containing dossiers on members of the 393d Bomb Squadron, the combat element of the 509th Composite Group.

Since skilled technicians were hard to find, Tibbets elected to keep them, threatening to send them back to prison for any dereliction of duty or security breaches.

In his book Project Alberta, Harlow Russ, a civilian scientist with Project Alberta who was part of the Fat Man bomb assembly team, recounts that during the flight he asked Uanna why all the military people on the plane were armed, and Uanna informed him that while the islands that they were stopping at were held by US forces, they would be flying over or close to other islands that were still occupied by the Japanese.

He mentioned this to Uanna "who seemed to know everything",[15] and he told Russ that it had most likely been taken by one of the Japanese soldiers holding out in caves and tunnels on Tinian, who made periodic raids in search of food.

[19] After the subsequent unconditional surrender of Japan, he accompanied the Manhattan Project team sent to survey the damage, spending four weeks in Nagasaki.

He returned to Boston, where he was admitted to the bar in 1946,[2] and practiced law and engineering, but was recalled to active duty in October 1946 to conduct an investigation into reports that servicemen had tried to sell pictures of the atomic bomb to The Baltimore Sun.

Amidst allegations from Senator Joseph McCarthy about the presence of Communist sympathizers in the Army and State Department, Uanna's expertise in countering subversion won him the position.

He then published the Protection of Dignitaries Manual and developed the handbook used at the training school for Marine Security Guards assigned to U. S. embassies, legations and consulates overseas.

[5] Dulles became ill in late 1958 and was replaced by Christian Herter, after which Uanna was posted overseas to Addis Ababa, Ethiopia, as an administrative officer at the U.S. Embassy.

[28] Uanna has also been portrayed by Stephen Macht in the 1980 TV movie Enola Gay: The Men, the Mission, the Atomic Bomb[30] and Minor Mustain in the 1995 Japanese/Canadian film Hiroshima.