Department of Homeland Security Secretary Kirstjen Nielsen defended her agencys role at the U.S. border with Mexico on Sunday, saying there was no family separation policy .

This misreporting by members, press and advocacy groups must stop, Nielsen wrote in a series of tweets Sunday evening. It is irresponsible and unproductive. As I have said many times before, if you are seeking asylum for your family, there is no reason to break the law and illegally cross between ports of entry.

We do not have a policy of separating families at the border, she continued. Period.