Garret Fitzgerald banned Soviet airlines from Shannon at the request of Ronald Reagan
Ireland agreed to ban Soviet airlines from the tarmac at Shannon just 10 days before the Cold War narrowly avoided nuclear catastrophe.
State papers released under the 30-year rule show US president Ronald Reagan sent a direct request for Taoiseach Garret FitzGerald to stop Aeroflot stopovers after a civilian airliner was blown out of the sky.
The blanket ban was ordered after the Soviets shot down Korean Air Lines Flight 007 on September 1, 1983 near Sakhalin island in the Sea of Japan after it strayed into Russian air space.
All 269 passengers and crew, including US congressman Larry McDonald, were killed.
In a strongly worded two-page letter, Mr Reagan tried to rally international opposition to the Soviets and called for co-operation and support among friends.
"The Soviet action represents a challenge to the international community. It would be a tragedy if we do not collectively respond in a resolute and clear manner to this action," he wrote.
Within weeks Cold War tensions were at their highest since the Bay of Pigs crisis in 1962.
According to leaked reports the world was a red button away from a nuclear World War Three after a Russian army early warning missile detection system gave a false alarm that the US had launched a strike.
A month or so later as the Kremlin attempted to keep the tech breakdown quiet while continuing its spy operations, enemies in Nato cranked tensions to their peak by simulating the early stages of nuclear war in operation Able Archer.
The period is regarded by many military and political historians to be the closest the world came to nuclear war.
Mr FitzGerald confirmed Aeroflot would be banned from Shannon on September 16, 1983, 10 days before the fault in the Oko missile detection system in Moscow.
Irish and US officials had already had private talks on the issue and considered a ban should initially be 60-90 days, "until the Soviet Union responds to our very real concerns".
Dr FitzGerald wrote a four-page letter back to Mr Reagan to confirm that Aeroflot would not be allowed to pick up or set down passengers at Shannon Airport on flights destined for Moscow.
He also said the government had deferred a decision on an application by Aeroflot for landing rights at Shannon for flights coming and going from Lima in Peru and Havana in Cuba.