The European Union will require American citizens to acquire a travel visa starting in 2021 before entering the Schengen Treaty area, which includes most of The Continent. Once the United Kingdom leaves the bloc, U.S. citizens will not require a visa to enter the U.K.

The new European Travel Information and Authorization System (ETIAS) visa will be required for all US citizens who want to enter any of the 26 Schengen-zone countries, reported The Independent.

The EU said the new restrictions were drawn up "to avoid any further problems with illegal migration and terrorism" but stressed that the ETIAS visa, once obtained, would be valid for three years.

"The ETIAS visa for Americans is a multiple-entry visa with few restrictions in order to promote tourism while maintaining a high level of international security," a spokesperson for the EU said in a statement.

The development seems to be a response to the United States requiring a visa from some EU member countries in Eastern Europe due to terrorism concerns.