A US Congressman says Russia's planned military exercises off Irish waters are designed to "push the envelope and test the West".
Irish-American Democrat Congressman Brendan Boyle was speaking as Ukraine's leaders have appealed for calm and reassured the nation an attack from Russia is not imminent.
This is despite the neighbouring country making combat readiness inspections close to its border.
Russia has informed Ireland it plans to carry naval exercises in waters around 240km off the southwest coast in early February.
The area is within Ireland's Exclusive Economic Zone (EEZ), but not her territorial waters.
Congressman Boyle told The Hard Shoulder the idea of Russian exercises off the Irish coast is 'shocking'.
"I remember my grandfather - who grew up in Easkey, Co Sligo - as a boy looking out for the German's, if they were coming during World War II.
"I thought those days were over - that anyone on the coast of Donegal or Kerry would now have to be watching for the Russians - it's completely shocking.
"It is again another way in which [Russian President] Vladimir Putin likes to push the envelope and test the West to see what our resolve will be like".
And he says the current situation is more about President Putin, than inaction by others.
"We are eight years into this war of Russian aggression against Ukraine, so in many ways this is not new.
"It's more a reflection of the resolve of Vladimir Putin to regain what he sees as the lost glory of the fallen Soviet empire.
"Vladimir Putin once said that the collapse of the Soviet Union was the greatest geopolitical catastrophe of the 20th century.
"So that's the mindset of the Russian leader that we're dealing with.
"And if we're not sober-minded about it, we could end up making a mistake in this latest crisis".
Congressman Boyle says President Putin sees Russia as being "disrespected" by former Soviet states.
"A lot of these right-wing populists around the world have something in common: they takeover a country that they see once was great, lost that greatness and they somehow are chosen to restore this so-called lost glory.
"And that is the case with Vladimir Putin, and certainly the way that he treats the former Soviet republics that dare to assert their independence".
But he says it is hard to get into President Putin's head.
"I don't think anyone knows what Vladimir Putin in the end really wants.
"No one can read Vladimir Putin's mind.
"I will say obviously the fact that he first invaded Ukraine about eight years ago, in the east, has not gone further - and this has been happening as I mentioned for quite some time.
"So that would be evidence that he's not necessarily anxious to launch some further incursion or further invasion.
"I do think there is a hope here that we can at least reach a stalemate".
And Congressman Boyle says actions by Russia cannot go unchecked.
"This is real, and it's exactly why I believe the US with our traditional NATO allies allies needs to assert itself.
"History is filled with examples of aggression in Europe being allowed to go unchecked, and we all know what that leads to.
"This is a serious moment - I do believe that we can be successful in pulling back from the brink, but I don't think it will go away by ignoring it".
Ukrainian President Volodymyr Zelenskiy said late on Monday that the situation is "under control" and there is "no reason to panic".
However, the Ukrainian government has acknowledged the threat from Russia is real and is due to accept a shipment of US military equipment to bolster its defences.
Moscow said earlier it was watching with great concern after the United States put 8,500 troops on alert to be ready to deploy to Europe in case of an escalation in the crisis.
The US move is in tandem with actions by other NATO member governments to bolster a defensive presence in eastern Europe.
It follows talks between US President Joe Biden a number of European leaders.
The White House said they reiterated their "continued concern about the Russian military build-up on Ukraine's borders and expressed their support for Ukraine's sovereignty and territorial integrity."
A statement added: "The leaders underscored their shared desire for a diplomatic resolution to the current tensions and reviewed recent engagements with Russia in multiple formats.
"The leaders also discussed their joint efforts to deter further Russian aggression against Ukraine, including preparations to impose massive consequences and severe economic costs on Russia for such actions as well as to reinforce security on NATO’s eastern flank."
Among those on the call on Monday were European Commission President Ursula von der Leyen, French President Emmanuel Macron, German Chancellor Olaf Scholz, Italian Prime Minister Mario Draghi, NATO Secretary-General Jens Stoltenberg, Polish President Andrzej Duda and British Prime Minister Boris Johnson.