The Trump administration is doubling down on its use of tear gas on women and children at the Mexican border, with Homeland Security Secretary Kirstjen Nielsen speculating without evidence that vulnerable people were used as “human shields” by migrants. Shocking photographs showed border agents deploying tear gas against people seeking asylum in the U.S. on Sunday, including young girls wearing diapers. In a lengthy statement late Monday, Nielsen speculated the women and children were used tactically by a migrant group. “It appears in some cases that the limited number of women and children in the caravan are being used by the organizers as ‘human shields’ when they confront law enforcement,” she wrote on Facebook. “They are being put at risk by the caravan organizers as we saw at the Mexico-Guatemala border. This is putting vulnerable people in harm’s way.” The unverified allegation is similar to one offered by President Trump on Monday evening, when he said “grabbers” take children to protect themselves from harm.