The Japanese government said Monday it will tighten border controls for travelers from three U.S. states, Finland and some other areas in response to the spread of highly contagious variants of the novel coronavirus.

In a set of changes to border control measures taking effect Thursday, those arriving from the U.S. states of Indiana, Kansas and Texas, as well as Finland, will be asked to stay in government-designated facilities for three days after arrival and take additional virus tests on the third day.

The same measure will also be applied to travelers from Georgia, Zimbabwe, Tanzania, Luxembourg and five Russian oblasts including Astrakhan.

Japan will also shorten the quarantine period of 10 days on visitors from Afghanistan to six days in designated facilities, and subject them to more coronavirus testing on the third and sixth days after arrival.

They will still be requested to undergo self-isolation for 14 days after entering Japan.