Foreign Affairs Minister Simon Coveney says a Russian diplomat to be expelled from Ireland was not chosen at random.
It comes as an Irish diplomat is expected to be expelled from Russia, in retaliation for the expulsion of one of their officials here.
The Tánaiste Simon Coveney confirmed the move on Tuesday as a mark of solidarity with the UK, who is holding Moscow responsible for poisoning a former spy and his daughter.
Sergei and Yulia Skripal were attacked with a nerve agent in Salisbury earlier this month.
Mr Skripal (66), a military intelligence officer, had been convicted and jailed in Russia for spying for MI6.
The Taoiseach Leo Varadkar and Tánaiste Simon Coveney have both defended the decision to expel a Russian diplomat.
Speaking to Pat Kenny, Mr Coveney said the diplomat chosen was not done so at random.
"This wasn't somebody just randomly chosen.
"There are 29 people working in the Russian embassy in Dublin - it's a big embassy - 18 of them are diplomats.
"We asked for advice from our intelligence services, from the gardaí and the Defence Forces - we have intelligence in both - and we asked them to say 'Look, if we were to ask somebody to leave, is there somebody that you would recommend that we should ask to leave?'
"And they made a recommendation and that's the person that we've asked to leave".
On Tuesday, Mr Varadkar said: "In relation to our neutrality, Ireland is a neutral country - we do not join military alliances, we will not be joining NATO, we will not be part of a European army.
"However when it comes to terrorism, assassinations and the use of chemical weapons and cyber-terrorism we are not neutral one bit.
"And we are joined of course in expelling diplomats with other countries that are also neutral, including Finland and Sweden, who have taken the same course of action as us."
The entrance to the Russian embassy in Dublin | Image: Brian Lawless/PA Wire/PA Images
While Mr Coveney added: "It is true that we are not in a position to independently verify the United Kingdom’s assessment of responsibility for Salisbury.
"But I underline that the evidence advanced by the UK, and confirmed by other key countries, convinced all 27 other EU leaders, and has impelled them to act."
"We had a choice to make - either to act in solidarity with our closest neighbour or to sit on our hands and do nothing.
"We had an obligation to act and to send a clear signal that what happened in Salisbury was unacceptable. We recognise it is important to maintain good relations with Russia, but we needed to respond".
Russia Today journalist Bryan MacDonald told Newstalk Breakfast earlier this will see retaliation from Moscow.
"I can tell you for sure Russia will expel an Irish diplomat as a consequence, and that will happen in the next couple of days.
"Really the Irish move is symbolic, and the Russian reply will also be symbolic - in a sense that everybody knew what the outcome of this tête-à-tête was going to be".
"What the Russian's see as the British over-reaction, or wrongful reaction, contributed to consolidating support amongst Russians - which feel their country's been victimised.
"That's the situation, that's the reality on the ground.
"Whether the Russian government took part in the poisoning or not - well, there's no evidence of it - but the Russian people certainly don't believe their government took part.
"They believe there was another issue at play".