Brexit has arrived in Britain, but American travelers need not worry about it affecting their travels, at least for now.

The action, which follows more than three years of parliamentary skirmishing and basically divorces Britain from its former partners in the European Union, now enters a transitional phase. For the rest of the year, officials will work out details of how trade and customs and travel issues will be dealt with.

But for American travelers headed to Britain, a European Union country or some combination of those, no document or procedural requirements will change until January 2021 at the earliest. The same is true for Britons traveling abroad and for citizens of EU countries heading to Britain.

Americans will continue to need passports for travel to the U.K., as Visit Britain notes on its website, but do not need visas, so long as “your reason for visiting meets the immigration rules.”

The 2020 transitional period is a short-term relief for many, especially those who feared the end of “frictionless” travel between the Republic of Ireland (which is part of the E.U.) and Northern Ireland, which is part of the U.K. (as are Scotland and Wales).

The logistics of Ireland’s borders are among the stiffest challenges negotiators face in the next 11 months, especially given the region’s long history of disputes and violence before the Good Friday 1998 agreement between the British and Irish governments. But for the rest of this year, those borders are not an issue for travelers.

The European Union, a group of now 27 countries that cooperate economically, has grown through more than 60 years of alliances and additions. Britain, which joined in 1973, is the first country to leave the organization.