While outwardly neutral in the Cold War stand off between east and west, the US and the Soviet Union, Sweden's defence and security forces were crucial to the country's influence in Washington, Svenska Dagbladet reports.
"The military cooperation between the US and Sweden was of much greater significance than previously known," says the author of a new doctoral thesis, Jerker Widén at the Swedish National Defence College (Försvarshögskolan), to Svenska Dagbladet.
Widén's thesis, entitled "Guardian, proxy, critic - Sweden's role in American security thinking 1961-1968", lays out Sweden's multiple role in the eyes of the US at the time, going further than previous studies which have mostly focused on diplomatic ties.
Widén writes that the US saw Sweden as the guardian of the western world in northern Europe. Sweden was seen as a crucial military-industrial base that must be kept out of Soviet hands.
"The role as guardian incorporated Sweden's role as an important Baltic power and a natural opponent to Soviet political and military dominance in the region. The US supported this role by means of military cooperation in the form of high-tech weaponry, military technical information and intelligence," Widén writes in his thesis.
The US embassy in Stockholm was populated by CIA agents and military attachés when the Cold War and the Vietnam War were at their most intense in the 1960s. Diplomatic representation was in the minority, Widén reveals.
Despite the Stig Wennerström spy scandal (Wennerström was arrested in June 1963 for spying for the Russians) and strong criticism over the Vietnam War by the then prime minister Olof Palme, Sweden-US relations were deepened further.
"From an American perspective Wennerström was one of the two major events of the 1960s. But instead of becoming angry at Sweden over Wennerström, respect increased as a result of the spy's arrest," Jerker Widén says.
Both the US and Britain were allowed to interrogate Wennerström, Widén reveals.
"The US Government did not view it (Sweden's criticism) positively but rather as something that had to be endured. According to leaders in Washington, this role was primarily a function of Sweden's choice to remain non-aligned in a region dominated by the Soviet Union," Widén concludes.
Despite being a staunch critic of the Vietnam War, Olof Palme was seen as a person the Americans could do business with.
Not least by the US military leadership at the Pentagon, Widén writes.
As a result of Palme's show of solidarity with North Vietnam in an infamous demonstration in Washington in 1968, the White House was in favour of punishing Sweden by withholding supplies of the Redeye anti-aircraft missile system.
But thanks to hard work by a delegation sent by Palme, the US military attaché in Stockholm, and primarily the Pentagon, the weapons were sent to Sweden as the country's role as a barrier to the Eastern Bloc was ultimately considered paramount.