The FBI says authorities are aware that the federal judge in Hawaii who ruled against President Donald Trump’s travel ban has received threatening messages.

FBI spokeswoman Michele Ernst said Thursday the agency is aware of reports of threatening messages against U.S. District Judge Derrick Watson and is prepared to help if necessary.

Watson blocked the federal government from enforcing its ban on new visas for people from six mostly Muslim countries and its suspension of the nation’s refugee program. He issued his ruling last week hours before the travel ban was to go into effect.

The U.S. Marshals Service is responsible for protecting federal judicial officials, including judges and prosecutors. The service says marshals don’t discuss specific security measures but does provide additional protection when warranted.