Critics of the Cold War nuclear arms race between the U.S. and the Soviet Union often pointed to the absurdity of storing such large caches of weapons: if the two countries, combined, had enough nuclear missiles to wipe out not only each other, but the the rest of the world, several times over, why was there a need for more? But both countries knew the growing arsenals were necessary to be able to overwhelm the opponent’s missile defense systems. As long as the defensive systems grew, so would the attacking ones; the first nuclear arms reduction talks took that as a fundamental starting point.

On this day, November 17, in 1969, members of the White House and the Kremlin met in Helsinki, Finland, to discuss limitations on missile defense systems, with a simultaneous reduction of missiles.

Negotiations went frustratingly long, complicated by deadlocks lasting months, but the two sides kept the dialogue going. Finally by 1971, President Richard Nixon and Russian Secretary of the Communist Party Leonid Brezhnev signed the Anti-Ballistic Missile (ABM) Treaty.