Irish citizens have been urged to leave Ukraine immediately amid fears Russia could launch an attack on the country in the coming days.
The Department of Foreign Affairs also urged Irish people to avoid travelling to the nation.
The move comes as the US warned of a potential aerial assault from Russia, which would see missiles and rockets launched towards targets in Ukraine, as early as Wednesday.
The eastern European country has appeared to be on the brink of an invasion from Russia for weeks.
More than 100,000 troops from the Kremlin have been moved to the border, though President Vladimir Putin has denied he plans to take the country.
A Department of Foreign Affairs spokesperson said: "Following intensive consultations overnight and this morning with EU partners in Kyiv and Brussels, and with other partners, the Department of Foreign Affairs has upgraded travel advice for Ukraine.
"We advise against all travel to Ukraine and ask citizens currently in Ukraine to leave immediately by commercial means.
"The updated travel advice is at dfa.ie/travel.
"Any Irish citizens requiring emergency consular assistance should contact the Department of Foreign Affairs at +353 1 4082000.
"In common with the Embassies of partner states, the Embassy of Ireland in Kyiv will remain open, with a small number of essential staff remaining. That situation will be kept under review.
"The Department has been in direct contact with all of those scheduled to travel to Ukraine for surrogacy purposes in recent days.
"The Department will continue to provide support to each of these individuals and families with advice relevant to their particular situation.
"We remain in ongoing contact at senior level with EU partners, as well as the UK and the US, regarding the wider political and security situation in and around Ukraine."
