A very short (and pre 1975) history of Irish/Russian relations.
An Taoiseach Micheál Martin has expressed the sincere and understandable concern that expelling the Russian Ambassador Yury Filatov could sever Irish/Russian relations and trigger the shuttering of both the Irish Embassy in Mosco and the Russian Embassy here in Dublin.
A not strictly reciprocal development given the imbalance in size between the representations… a point well made in this Irish Times article: https://www.irishtimes.com/news/ireland/irish-news/russia-still-plans-to-extend-dublin-embassy-s-espionage-role-say-experts-1.4814532
Relations between Ireland and Russia have been fraught at times and formal diplomatic representation only commenced in 1973.
Initially relations were cordial with the Irish giving the Soviet Union a loan of €20,000 in 1920 in return for czarist jewels (which were supposedly worth $25000 – Christies later valued them at £1600). The loan was repaid, without interest in 1949.
In 1934 Ireland voted to admit the USSR to the League of Nations, despite strong opposition from some in the League and also back home from Cumann na nGaedheal and the Catholic Church
In 1946 Ireland applied to join the newly formed United Nation, but its application was vetoed by Russia. Several times. Russia argued that Ireland was not eligible for UN membership as it was neutral in WWII and had not established diplomatic relations with the Soviet Union.
Responding to one of these vetoes de Valera told the Irish Times on 1 Aug. 1947 that:
If Russia, which attacked Finland, Poland, Estonia, Lithuania, can be regarded as qualifying as a peace-loving nation, it is difficult to see how a nation which kept the peace and scrupulously fulfilled all its obligations as a member of the League of Nations can rightly be regarded as not qualifying – but then…we have no diplomatic relations with Russia…
In reality the veto was less about Ireland and more about Cold War parity. Simple tit for tat. The west could not get an extra pro American UN vote without Russia getting one too. That said, it is known that Poland urged the Soviets to drop their specific objections to Ireland When Russia dropped its veto and Ireland was eventually admitted to the UN in 1955, it was as part of a 15 new UN member package (including Romania Hungary and Bulgaria).
At the UN Ireland was quick, under the leadership of Frank Aiken as Minister and Frederick Boland as ambassador, to be non-aligned on the Cold war, including backing a proposal to admit the People’s Republic of China and to advance a Nuclear Non-Proliferation Treaty. When this was eventually ratified in 1968, Russia invited Ireland to be the first to sign the treaty as recognition of the lead role Aiken had taken in its passing.
When Ireland sought to raise the developing crisis in Northern Ireland at the United Nations, it had the support of the USSR – with then Foreign Minister Paddy Hillery observing:
‘once you have dealt with the Irish bishops, the Russians are a doddle.’
Though the aim of securing a UN peacekeeping intervention failed, the Russians and others did facilitate Ireland raising the issue directly at the Security Council, though the UK was certain to veto it.
The move to formal diplomatic relations commenced informally in the early 1970s with the assignment of an official TASS representative in Dublin, a development which concerned the British as it was certain that he was a KGB officer and could use the common travel to slip quietly in and out of the UK. In 1973/74 formal relations commenced with the exchange of full ambassadors and the acquisition by the Russians of the 5-acre site that had previously housed the Irish Management Institute on Orwell Road in Rathgar.