The United States has announced that it will lift Covid-19 travel bans on air passengers in November if they are fully vaccinated and undergo testing and contact tracing.
Jeffrey Zients, coronavirus response coordinator for President Joe Biden, told reporters the new "consistent approach" would take effect in "early November".
The easing of travel restrictions, imposed 18 months ago by Donald Trump as the Covid-19 pandemic first erupted, marks a significant shift by Mr Biden and answers a major demand from European allies at a time of strained diplomatic relations.
The US restrictions were first imposed on travellers from China in January 2020 by Mr Trump and then extended to other countries in the following months, without any clear metrics for how and when to lift them.
Speaking in New York at the start of a five-day visit to the US, Taoiseach Micheál Martin said he was very pleased to hear the news.
"I had written to President Biden in August saying it was important that two-way travel between Europe and the United States resume," Mr Martin said.
"I pointed out to him the very high vaccination rates in Ireland right now and that the risk was much lower."
Asked if Mr Biden had replied to his letter, the Taoiseach said: "we haven't got a formal reply yet, but I think today's announcement is as good as it gets."
Minister for Foreign Affairs Simon Coveney said it is "something that we, along with our EU colleagues, have been advocating for a considerable time".
"We have alerted the US Administration to the high levels of vaccination within Ireland," Minister Coveney said.
"With 90% of Irish adults now fully vaccinated, I know this will come as very good news for many in Ireland, the Irish living in the United States, as well as our American friends with links to Ireland and the rest of Europe."
Ireland's Ambassador to the USA Daniel Mulhall has also welcomed the decision.
"This very positive development will bring welcome relief to so many Irish people who have been separated from family for the past 18 months because of the #travelban," he wrote in a social media post.
US recognition of AstraZeneca
While Washington has not authorized the AstraZeneca vaccine against Covid-19, a European commissioner has expressed hope that travellers from Europe inoculated with the jab will soon be able to enter the United States.
Thierry Breton, European commissioner for internal market, said the new order covers people vaccinated with jabs recognized by the US Food and Drug Administration (FDA).
The agency has not approved the AstraZeneca vaccine used by many European nations, however, Mr Breton said he spoke with White House pandemic response coordinator Jeff Zients who "sounded positive and optimistic."
However, Mr Zients told him that "for the other vaccines, for AstraZeneca in particular, their health agency would decide."
President Joe Biden in April of this year added new travel restrictions on India, barring most non-US citizens from entering the United States. Mr Biden also reversed plans by Mr Trump in January to lift restrictions on European countries.
The United States currently bars most non-US citizens who within the last 14 days have been in Ireland, Britain, the 26 Schengen countries in Europe without border controls, China, India, South Africa, Iran and Brazil.
There will be some exceptions to the vaccine policy, officials said, including for children not yet eligible to be vaccinated. The new rules do not yet apply to travellers crossing land borders with Mexico and Canada.
Airlines have heavily lobbied the White House for months to lift the restrictions, but were unsuccessful at having them lifted in time for the summer travel season.
The White House said in July it had concerns about the highly infectious Delta variant and a rising number of US Covid-19 cases.
The seven-day average of reported US cases has more than doubled since then.
Currently only US citizens, residents and foreigners with special visas are allowed to enter the United States from most European countries.
The travel restrictions had deeply irked EU and British authorities.
The European Union had recommended that member states reimpose restrictions on American travellers who had earlier been free to enter if vaccinated. US travellers have been allowed to visit Europe during the summer season.
Mr Biden's move comes on the eve of the UN General Assembly in New York, where the pandemic is due to be the headline issue.
It also comes amid diplomatic tensions, as the US and France spar bitterly over Australia's sudden announcement that it will be getting US nuclear submarines, ditching a previous French contract for conventionally powered submarines.