The Trump administration has blocked the ability of Harvard University to enroll international students, The New York Times reported Thursday. CNBC has requested comment from Harvard on the reported move, which comes amid an ongoing battle between the Ivy League school and the administration. "I am writing to inform you that effective immediately, Harvard University's Student and Exchange Visitor Program certification is revoked," Department of Homeland Security Secretary Kristi Noem wrote in a letter to Harvard, a copy of which The Times said it had obtained. This is breaking news. Please refresh for updates.