One of the nation’s largest teachers’ union is authorizing its members to strike if their schools plan to reopen without proper safety measures in the middle of the global pandemic.

The American Federation of Teachers, which represents 1.7 million school employees, issued a resolution on Tuesday saying it will support any local chapter that decides to strike over reopening plans. The group says school buildings should open only in areas where coronavirus infections are low enough and if schools enact certain safety measures.

The union’s president blasted President Donald Trump for ordering schools to reopen even as the virus continues to surge. Randi Weingarten called Trump’s response “chaotic and catastrophic,” saying it has left teachers angry and afraid.