The United States will begin enforcing a visitor registration law for Canadians who enter the U.S. via land borders, the New York Times reported on Tuesday, citing officials.

The United States had not been enforcing the rule for Canadians who entered via land borders. That is changing amid an escalating fight between the North American neighbors.

The United States is cracking down on long-term visits from Canadians by now requiring visitors in the U.S. longer than 30 days to register with the government. Those who are over the age of

Canadians staying in the U.S. for longer than 30 days — a norm for many snowbirds who spend their winters south of the border — will have to register and submit fingerprints with U.S. immigration enforcement.