TORONTO (AP) — Canada and the United States have agreed to extend their agreement to keep the border closed to non-essential travel to June 21 during the coronavirus pandemic.

Prime Minister Justin Trudeau says the border is a source of vulnerability so the agreement will be extended by another 30 days to help keep people in both of countries safe.

The restrictions were announced on March 18 and were extended in April.

There are some exceptions for border crossings. Essential workers like health care professionals, airline crews and truck drivers carrying essential goods are still allowed to cross, as are Americans returning to the U.S. and Canadians who are returning to their country.

Trudeau said Canada’s provincial leaders clearly wanted to continue the measures. Many Canadians fear a reopening.

The U.S. has more confirmed cases and deaths from COVID-19 than any country in the world, though its per capita numbers are well below many other nations.