“The international situation at the moment is such that any relaxation of border measures would be very risky,” Australia’s chief medical officer Brendan Murphy told a government inquiry on the country’s handling of the pandemic.

Murphy said border restrictions could be the last mitigation measure to be lifted, and would remain in place even if Australia succeeds in reopening businesses and relaxing social-distancing rules. Australia has seen an infection growth rate of less than 1 percent for the past 11 days, and as of Thursday had recorded about 6,500 cases with 67 deaths.

The government on Tuesday said its lockdown measures, in which public gatherings are mostly limited to two people and various businesses have been closed, have led to a “sustained and consolidated” decrease in the number of new coronavirus cases.

Various nations around the world have implemented restrictions on entry of foreign visitors, including the U.S. The Trump administration has halted “non-essential” travel across its borders with Canada and Mexico, and has banned foreign citizens from entering the U.S. from E.U. nations and China.

President Trump also signed an executive order on Wednesday halting certain types of immigration to the U.S. for 60 days.