US-bound international travelers must have proof of a negative COVID-19 test before arriving, and that requirement may soon be extended to domestic travel.

President Biden and his administration are reportedly considering implementing the same mandatory testing procedure for domestic flights to slow the virus’ spread. Currently, domestic air passengers have to acknowledge via online questionnaires that they aren’t experiencing any COVID-19 symptoms, but no other requirements are in place, except additional temperature checks and screenings conducted by some airlines and airports.

Although it’s not clear who would enforce such a requirement, Hawaii and Alaska serve as helpful examples, as both have required testing before entry for months.