Seoul, April 13 : All arrivals from the US to South Korea will be tested for the novel coronavirus within three days of self-isolation, starting from Monday onwards, health authorities said. The strengthened measure against COVID-19 began at midnight, Yonhap News Agency quoted the Korea Centers for Disease Control and Prevention (KCDC) as saying on Monday morning. It comes as confirmed cases from the US have been increasing steadily despite a gradual decline in domestic cases. KCDC data showed that 228, or 49.7 per cent, out of a total of 459 imported cases came from the US over the past two weeks. On Sunday, the number of imported cases was 24, with 18 of them coming from the US, followed by Europe with two. Since March 27, all entrants from the US have been subjected to strengthened quarantine measures as South Korea grapples with a surge in imported coronavirus cases, said the Yonhap News Agency. Passengers from the US who do not show symptoms of COVID-19, such as a fever, are required to self-isolate at home for two weeks. Those who show symptoms are required to undergo tests upon arrival. The country has also been enforcing two-week quarantine and virus tests for all long-term arrivals from Europe, regardless of symptoms. Soth Korea's new virus cases stayed around 30 for the third straight day Monday due to a social distancing drive and enhanced quarantine measures. The country reported 25 more cases of COVID-19, bringing the nation's total infections to 10,537. Of the newly added infections, 16 were imported. The death toll stood at 217. /IANS