A "quarantine" of Cuba, as it was termed by President Kennedy.
In an address to the nation in October 22, 1962, President Kennedy told of surveillance that revealed Soviet missile sites were observed as part of military build-up in Cuba. He said he would demand that the USSR remove all offensive missiles from Cuba or the US would place Cuba under a "quarantine." A more usual term normally would be a "blockade," but Kennedy avoided that loaded term because that could be interpreted by the USSR as an act of war.