WASHINGTON (Reuters) – Groups representing the U.S. travel industry and airlines on Friday voiced opposition to mandatory quarantines for air passengers arriving in the United States from overseas a day after President Joe Biden signed an order to take that step.

Biden on Thursday issued an executive order directing federal agencies to require international air travelers to quarantine upon U.S. arrival. His administration also is implementing effective next Tuesday a requirement that all U.S.-bound passengers ages 2 and above get negative COVID-19 test results within three days before traveling.

The U.S. Travel Association, an industry group representing businesses including hotels and airlines, said the mandatory negative test requirement eliminates the need for quarantining returning passengers, a step that it said “could be extremely difficult to enforce.”

The group represents a range of travel-related businesses including hotels, car rental firms, tourism agencies and entertainment companies.

At a briefing on Friday, White House spokeswoman Jen Psaki did not provide details on what actions the administration might take to enforce the quarantine requirements.

Airlines for America, a group representing major U.S. airlines, separately said it hoped the White House will recognize that “testing can be used to safely resume travel without quarantines, which are difficult to enforce and often prove ineffective.”

The U.S. Centers for Disease Control and Prevention (CDC) recommends a seven-day quarantine for air travelers arriving in the United States after being tested.

Biden also directed federal agencies to implement a mask-wearing mandate for interstate transportation for passengers aboard trains, buses and air travel. The president directed the agencies to make recommendations to “impose additional public health measures for domestic travel,” which administration officials said could include a negative COVID-19 test before flying domestically.

U.S. Travel Association Chief Executive Roger Dow said in a statement the group does not think making testing mandatory before domestic travel is “feasible or viable.”

The Biden administration has said it plans to reimpose entry bans on most non-U.S. citizens who have recently been in Brazil and most of Europe. Former President Donald Trump issued an order on Monday lifting the restrictions, effective Tuesday.

Biden issued a separate order on Wednesday instructing agencies to require the use of masks in federal buildings and on federal lands.

Reporting by David Shepardson; Editing by Will Dunham