A former advisor to Ukraine's foreign minister says the situation with Russia is 'the most serious escalation' so far.
Cormac Smith worked in his role from 2016 to 2018, having previously held senior positions in several UK local authorities.
It comes as both the US and UK governments are advising their citizens in Ukraine to leave.
They are also advising against travel to Ukraine.
Irish citizens have been told to avoid non-essential travel to the country.
In a statement on Friday, the Department of Foreign Affairs says it is "in ongoing contact at senior level" with EU partners, as well as the UK and the US.
It says coordination in respect of consular and security contingency planning "will continue through the weekend."
It also says there are no plans to withdraw staff from the Irish embassy in Kyiv at this time.
But it adds it is in "ongoing direct contact with Irish families scheduled to travel to Ukraine for surrogacy purposes and will continue to provide advice and assistance."
Cormac told The Hard Shoulder Russia's President Vladimir Putin is trying to put the Russian Empire back together.
"My assessment of where we are at the moment is not in a great place.
"Russia has been waging a low-level war on Ukraine for almost eight years.
"Putin is on record as saying that he believes the break-up of the Soviet Union was the greatest geopolitical disaster of the 20th century.
"He wants to put - what he sees as - the Russian Empire back together, or as friends of mine in Ukraine would call 'Soviet Union 2.0'".
Cormac says the reason Russia has its eyes on Ukraine is two-fold.
"Ukraine - although it was one of 15 states - apart from Russia was the richest part of the Soviet Union.
"It accounted for over 40% of industrial output.
"He wants Ukraine back for the wealth that it embodied, but secondly: there is no greater threat to Putin and his cronies in the Kremlin than a successful, democratic Ukraine on his doorstep.
"That is why, effectively since 2014, Russia has been doing everything it can to retard Ukraine's progress towards the West and towards full democracy".
'Arming Ukrainians to the teeth'
He believes as many as 140,000 troops are on Ukraine's border.
"This is the most serious escalation we have seen so far.
"There's possibly as many as 140,000 Russian troops massed on the Ukrainian border.
"The Americans have told American citizens to leave the country immediately.
"There is a serious fear that an invasion could happen".
And he says while Ukraine is not a NATO member, meaning the group will not "put boots on the ground", there are other options.
"What NATO countries, and the Americans and the Brits in particular, have been doing in increasing amounts is arming the Ukrainians to the teeth and giving them the exactly the sort of defensive weapons they need.
"The second thing they want is real sanctions ramped up - including going after probably the top 50 oligarchs who again are Putin's buddies.
"And the third thing that the Ukrainians need is the West speaking in one voice.
"It has up to recently been too easy for Putin to divide and conquer the West - there are some promising signs that unity is growing stronger and stronger".