Donald Trump's trade sanctions could have a "catastrophic" effect on the economy of rural Limerick, a TD has warned.
Hundreds of jobs could be put at risk after the billionaire oligarch behind the Aughinish Alumina plant was hit with sanctions earlier this month.
Some 450 employees and a further 250 contractors could be affected.
Fianna Fáil TD Niall Collins said: "There is a genuine fear among the community if there are job losses it would have a catastrophic economic impact on the region."
The US government has targeted seven Russian oligarchs and 17 Russian government officials with sanctions for what it called "malign activity" around the world.
Among them was Oleg Deripaska, from UC Rusal which owns the sprawling Limerick plant.
In a statement the Irish Government said officials were keeping the situation under review and were working closely with the company.
A spokesman for the Department of Business, Enterprise and Innovation said: "The Government is very much aware of the risks and is closely engaging with Aughinish Alumina.
"The Department of Business, Enterprise and Innovation, IDA Ireland and the Department of Foreign Affairs and Trade, working together, continue to keep the situation under careful review, and IDA Ireland remains in regular contact with the company.
"The Tanaiste and the Minister for Business, Enterprise and Innovation have both been in contact with the CEO, confirming that the Government will do everything possible to assist the company.
"Likewise, the CEO of IDA Ireland has been liaising with the CEO of the Aughinish plant.
"The Taoiseach also met with senior management, including the CEO, in Limerick.
"It will be some time before we are in a position to fully assess the potential impact on the Irish economy of the sanctions announced by the US Department of the Treasury on April 6, which have not yet become fully effective.
"The Government continues to closely monitor developments, collaborating across departments, as the situation evolves."
Senior Trump administration officials said the penalties were part of a concerted and ongoing effort by the US to push back Russian President Vladimir Putin's government and put pressure on those in his circle.
No one from Aughinish Alumina was available to speak.
However, sources close to the company said it was business as usual.
One source, who said he had been instructed not to speak publicly on the matter, said: "Workers are going about their jobs as normal.
"There is bauxite coming in and alumina going out.
"There has been a slight decrease in production but that might have to be cranked up again.
"It is not a storm in a teacup but the workers have faith in the management and faith in the government that it will be sorted.
"They are concerned about some of the comments which could create panic.
"My understanding is that there is a lot of work going on in the background."
Aughinish Alumina was built more than 30 years ago.
It is a significant contributor to the local economy with average salaries estimated to be in the region of about 80,000 euros-a-year.
Meanwhile, the Russian Ambassador to Ireland Yuri Filatov was asked about the sanctions during a press briefing last week.
He said the factory owner, Russia and Ireland are all on same wavelength.
"We are on the same wavelength.
"Sanctions are not good, that many jobs and the health of a good enterprise is at stake, we certainly repudiate this sanctions policy on the part of the United States which is in this case or in any other cases seem to be extra territorial and imposing on other countries something in Washington they think is in their interest," he said.