President Trump tweeted on Sunday that border security officials continued their "full efforts ... to stop the onslaught of illegal aliens" attempting to travel to the U.S. southern border via a large migrant caravan — while also describing such caravans as "a disgrace to the Democrat Party." "People have to apply for asylum in Mexico first, and if they fail to do that, the U.S. will turn them away," Trump tweeted. "The courts are asking the U.S. to do things that are not doable!"