The State Department, concerned about the new variants of the coronavirus as well as new restrictions on entering the U.S. from a foreign country, is warning Americans who are thinking about traveling to reconsider their plans.

“If you’re overseas right now, it could be harder to come home for a while,” said Ian Brownlee, the State Department’s acting assistant secretary for consular affairs, according to the Miami Herald. “Everyone needs to be prepared to be potentially seriously disrupted in their trip.”

Brownlee pointed out that new strains of the virus were detected in Latin America and the Caribbean, while at the same time the U.S. put in new requirements for anyone traveling to the U.S. from overseas to produce a negative COVID test upon arrival – American citizens included. Anyone failing to do either will be denied boarding by the airlines and will be responsible for any additional lodging costs.

At least 16 countries and territories, including the United States, have confirmed the presence of at least one of three emerging variants.

“The bottom line message is: This is really not the time for people to be engaging in discretionary travel and that all travel should be postponed until we get a better handle on getting this virus under control, and accelerating our vaccination strategies,” Brownlee said.

Dr. Marty Cetron, director of the U.S. Centers for Disease Control and Prevention’s global migration and quarantine division, said the new variants could be more contagious than the main virus that has plagued the world for more than a year now.

“They all suggest that they are potentially more contagious than the current circulating predominate virus,” Cetron said. “They can quickly become the predominant virus that’s circulating and several of them have presented challenges in …evading some of the natural immunity and challenges toward looking at our vaccine solutions.”