Canada is looking to strengthen surveillance at US border crossings as discussions continue between the two countries about when and how to reopen the border to nonessential travel.

“We are looking at stronger measures to make sure that we’re following up appropriately on people who come over,” said Canadian Prime Minister Justin Trudeau during a news conference in Ottawa Tuesday.

The Canadian government is looking at administering questionnaires, contact tracing apps, temperature and medical history checks.

“We’re going to be very, very careful about reopening any international travel, including the United States before we feel that it is time,” Trudeau said.

Some background: Canada and the US agreed to close the border to nonessential travel in March and the current agreement, already extended, expires May 21. There is still no decision on whether the border agreement will remain in place beyond that date.

Canadian premiers and mayors across the country have expressed concern about fully reopening the border as the US continues to deal with Covid outbreaks and significant community spread.

“Preventing transmission from outside of Canada into Canada, once we have controlled the spread within Canada, will be an essential part of ensuring that we don’t fall back into a second wave that could be as serious as this wave we’re going through, or even more so,” Trudeau said.