He explained that rock-throwers prevented agents from aiding women and children being passed over concertina wire that had been laid beyond the fence on the US side.
Fox & Friends reminded viewers of the current conflict unfolding on the Southern U.S. border featuring yet another skirmish between American border patrol and migrants reportedly trying to illegally scale a border wall near Tijuana. The agency says it saw members of the group try "to lift toddler-sized children up and over the concertina wire". Twenty-five people were arrested after crossing into the US, including two teenagers.
An estimated 150 migrants, including children, tried to climb over a border fence in the early hours of the new year.
U.S. Customs and Border Protection (CBP) said in a statement the gas was aimed upwind of people throwing rocks on the Mexican side who obstructed agents from helping the children being passed over razor wire.
The incident took place on the New Year's Eve, with migrants telling Reuters that they expected security to be lax during the first night of 2019 due to celebrations. Shortly after, migrants began throwing rocks over the fence at CBP officers.
In November, after a group of migrants tried to rush the border, McAleenan defended the use of tear gas: "As the events unfolded, quick, decisive and effective action prevented an extremely risky situation".
Shortly after the New Year began, dozens of migrants stood on a hill from which they could see U.S. border agents, who watched them closely.
Per use of force policy, the incident will be reviewed by the Border Patrol's Office of Professional Responsibility. "However, this incident needs to be examined within the broader context of USA policies at the border". The rest asked to be transported back home or dispersed to other parts of Mexico.
The issue of border securityhas paralyzed the government after President Trump demanded an additional $5 billion in funding for securing the frontier and Democrats refused.
It comes as the United States federal government remains shut down as President Donald Trump and Congress argue over funding for his proposed border wall.
Border Patrol agents are beginning to feel the effects of the partial government shutdown.
"Migrants who participate in these violent events who are fully identified will be deported immediately", the Ministry of Interior said in a statement.