Travelers from dozens of countries (42 in total) may be asked to provide their social-media history from the past five years as a condition for entering the United States.

The new proposal presented by U.S. officials will affect people from many countries who are allowed to visit the U.S. for 90 days without a visa, as long as they have completed the Electronic System for Travel Authorization (ESTA) form. This includes Greek citizens.

The proposal document was submitted by the Customs and Border Protection (CBP) agency and the Department of Homeland Security (DHS), to which the agency belongs. It has already been published in the Federal Register, according to the BBC.

The proposal does not specify the exact details of the information that will be required from the social-media history.

In addition, travelers will be required to submit the phone numbers and email addresses they have used over the past five and ten years respectively, as well as more information about their family.

Currently, the ESTA requires a relatively limited amount of information from travelers, along with a one-time payment of $40 (30 pounds).

The measure is part of the U.S. government’s policy—under the Trump administration—of tightening border security for national-security reasons.

The U.S. expects a high influx of tourists in 2026, as it will host the men’s FIFA World Cup along with Canada and Mexico. In 2028, Los Angeles will host the Olympic Games.

The Trump administration had already required foreign nationals to disclose their social-media accounts when applying for student visas or H1B visas for skilled workers, which also carry a much higher fee.