The Department of Homeland Security on Monday vowed to prosecute Central American migrants in a “caravan” near the U.S. border if they try to enter illegally and Attorney General Jeff Sessions said the effort was a “deliberate attempt to undermine our laws and overwhelm our system.”

With the caravan on the final stage of its journey — about 440 miles, or a 12-hour journey by bus or train from the southern border — DHS Secretary Kirstjen Nielsen, acting under orders from President Donald Trump, said the agency was monitoring the group’s movement and those who enter the U.S. illegally will be referred for prosecution. There are about 500 migrants in the caravan.

“Pockets of the original, so-called ‘migrant…