A 1941 West Point graduate, during World War II he served as an Army officer providing security for the Manhattan Engineer District; this undercover project sought to build the first atomic bomb.

He personally escorted the plutonium hemispheres that formed the core of the Fat Man nuclear weapon to Tinian, the island in the western Pacific from which the raid on Nagasaki was staged.

Following the surrender of Japan, he accompanied a team of Manhattan Project scientists who conducted the radiological survey and compiled the final damage report on the atomic bombings of Hiroshima and Nagasaki.

Then at CIA de Silva, still in the Army, though working under Richard Helms, performed the delicate task of vetting former OSS agents, especially European refugees with "murky" backgrounds.

[12] There he minded an unpleasant Russian colonel permitted to travel widely in the American zone, in order to speak with displaced persons; the Soviet offered them return to the USSR, a very unpopular option.

Although as an Army officer he obtained his Russian language training, de Silva made contact with various CIA agents posted to central and eastern Europe, which was very tense terrain at the start of the Cold War.

The CIA then began to replace the Army intelligence in its role doing liaison work, begun during the Allied occupation of Germany with the reconstituted Gehlen organization.

[16][17] A major part of de Silva's job in Pullach was to assist with the various West German efforts to collect information from the occupied Soviet Zone of Germany.

Awareness of the status of these agents was tricky, as sometimes a V-mann might be turned or doubled by opposing Communist officials, corrupting any subsequent information.

[18][19] Back at CIA headquarters, then located in Washington near the Lincoln Memorial, de Silva in 1951 briefly worked in the Foreign Intelligence Staff under the veteran Eric Timm.

One CIA operation in Russia that did meet with success involved a joint reconnaissance mission with the Navy, sending a small team to a newly built Soviet airfield in eastern Siberia.

[20][21] With the purpose of resigning as an Army officer de Silva had in 1951 been interviewed by the formidable General Walter Bedell Smith, then the DCI.

In early 1955 Frank Wisner, the head of CIA's Clandestine Service, assigned de Silva to Vienna as deputy COS.

The CIA station in Vienna remained active and contrived to surreptitiously overhear preparations made by a neutral power (probably India) for a conference in Moscow.

The CIA in Vienna focused its resources and attention on the tense, life-or-death sequence unfolding in Budapest, about 200 kilometres (120 mi) down river.

While the US ambassador waited for instructions from Washington, de Silva telephoned the Blue House and spoke with the Defense Minister Kim Chong Yol, warning him of danger.

The 1960 April Revolution in South Korea eventually caused new elections, which resulted in a new democratic government led by the then popular Chang Myon.

At a breakfast at the US Embassy, de Silva saw an animated U.S. president converse with Korean dignitaries, including the leading candidate Chang Myon.

[41] The following year in May ROK General Park Chung Hee and accomplice senior officers staged the 1961 South Korean coup d'état, overthrowing the elected regime of Chang Myon.

The discredited police of the Rhee era could not maintain order, while massive student demonstrations often worked to manipulate and debilitate the regime's agenda.

In Hong Kong de Silva found the case officers speaking Mandarin or Cantonese, and that they were considered "old China hands," having done repeated CIA tours in East Asia.

The British who governed Hong Kong remained mindful of the nearby People's Republic of China (PRC), which not only had substantial business entities located in the city, but also controlled its water supply.

Chinese seeking asylum were interrogated by the British, who thereby gathered "sociological intelligence" on the Communist regime, current information about rations, the economy, and morale.

Since, John H. Richardson, a "long-time friend" of de Silva, had been COS in Saigon, until that October when he'd been fired by the new Ambassador Henry Cabot Lodge.

In their inspection Colby and de Silva focused on the government's conflict with the Viet Cong insurgency, investigating the cities and the countryside.

The "soft" technique the CIA taught caused the subject being questioned to realize that his or her "well-being was best served by responding truthfully".

[63][64]The Viet Cong enemy, according to de Silva, had two strategies: 1) ambush the military; and 2) terrorize the rural people and civil leaders.

When the current COS in Bangkok was scheduled to leave, Colby heeded Martin's request and recommended de Silva to Fitzgerald who approved.

[79][80] Once when traveling from Bangkok to Saigon, de Silva had sought without success a meeting with Robert Komer, head of CORDS, in order to challenge his approach to pacification.

[82][83][84] When the CIA's Far East chief William Colby visited northeast Thailand in 1967, McGehee was pleased to show him the results of his counterinsurgency surveys.