Winston Churchill , the British wartime Prime Minister , made an attack on the Irish Government and in particular Éamon de Valera in his radio broadcast on VE Day . Churchill maintained that the British government displayed restraint on the Irish state while the de Valera government were allowed to " frolic with the Germans " . Churchill maintained that the British could have invaded the Irish state but displayed " considerable restraint " in not doing so . De Valera replied to Churchill in a radio broadcast : Mr. Churchill makes it clear that in certain circumstances he would have violated our neutrality and that he would justify his action by Britain 's necessity . It seems strange to me that Mr. Churchill does not see that this , if accepted , would mean that Britain 's necessity would become a moral code and that when this necessity became sufficiently great , other people 's rights were not to count .... this same code is precisely why we have the disastrous succession of wars ... shall it be world war number three ? Ireland applied to join the United Nations in 1945 , but this was blocked by an objection by the Soviet Union in the security council . Sean MacBride considered that the UN boycott of Ireland was originally agreed at the 1945 Yalta Conference by Churchill and Joseph Stalin . Despite MacBride 's belief , the United Kingdom fully supported Ireland 's applications to join the UN . ( Ireland eventually joined the United Nations in 1955 . ) During the Cold War , Ireland maintained its policy of neutrality . It did not align itself officially with NATOor the Warsaw Pact either . It refused to join NATO because Northern Ireland was still a part of the United Kingdom . Ireland offered to set up a separate alliance with the USA but this was refused . This offer was linked in part to the $ 133 million received from the Marshall Aid Plan
Yalta Conference
Yalta Conference
Irish neutrality