Three people have been confirmed to have Covid-19 on Guam, the second place in the Pacific to have the coronavirus.
Governor Lou Leon Guerrero has declared a state of public health emergency in the US territory, which is also a hub for travel in the North Pacific.
"All three confirmed cases are currently in isolation," Ms Guerrero said in a statement.
"Preliminary investigation has indicated that all three had travel connections - two recently travelled to the Philippines and the third had a family member who recently returned from Japan."
The two who travelled from the Philippines were on a United Airlines flight from Manila on flight UA189 on 29 February.
At a later news conference, Ms Guerrero urged anyone who was on that flight to self-isolate, along with anyone who had flu-like symptoms.
"This is what we prepared for and while we must expect more cases, everything that can be done is being done," she said.
All government travel on Guam has been cancelled, as have events with more than 100 people.
Ms Guerrero said while she could not mandate travel restrictions, she urged everyone to avoid non-essential travel.
Guam is the second territory in the Pacific to confirm cases of Covid-19, after French Polynesia declared three cases last week.
On Thursday, French Polynesia's member of the French National Assembly, Maine Sage, became the first person in the Pacific confirmed to have Covid-19, having contracted it while in Paris.
Two more people - an acquaintance of Ms Sage and a Swiss tourist - have since tested positive for it.
Since then, cruise ships have been banned in French Polynesia, and a number of flight restrictions have been imposed.
French Polynesia's tourism minister, Nicole Bouteau, said the economy would go through dark times in the coming weeks, as a result of the measures.
Meanwhile, airlines linking French Polynesia with France are scrambling for alternatives to cope with restrictions imposed by the United States on flights from Europe.
French Bee said it would maintain a weekly flight between Paris and Tahiti by stopping Guadeloupe instead of California, while Air Tahiti Nui is in talks to fly through Canada instead.
In Tahiti, the news of the positive coronavirus cases prompted a rush on supermarkets, and many sporting events were cancelled this weekend.
However, the government said schools would remain open this week.