Japan announced Monday it would be barring entry of all foreign visitors as the Omicron variant spreads rapidly across the globe.
It joins Israel in implementing some of the strictest border measures yet since the new strain was first discovered in South Africa.
Prime Minister Fumio Kishida says the ban is effective Tuesday at midnight.
He told reporters that Japanese arrivals from specified nations would be sent to quarantine.
"With regards to Japanese nationals, in addition to the nine countries including South Africa (in which arrivals have been suspended), if they are coming back to Japan from (an additional) 14 countries and areas where (Omicron) infections were confirmed, we will respond to the risk by strictly isolating them at designated facilities."
Kishida's announcement comes just a few weeks after his administration eased quarantine measures on foreign business travellers to help boost the economy.
The World Health Organization has named Omicron a "variant of concern" but warned that weighing its severity could take "days to several weeks."
It's urged caution against hasty travel bans - but that hasn't stopped most countries from scrambling to tighten border controls over the past week.
Japan has not detected any Omicron cases so far, with one coronavirus case from Namibia being tested for the new variant.