The U.S. military will "CLOSE OUR SOUTHERN BORDER" with Mexico if officials there don't soon stop the northward push of a massive migrant caravan, President Trump warned Thursday, amid reports the procession had swelled in size to about 4,000 people. Trump's latest threat against the caravan — which originated in Honduras and is bound for the U.S. in a bid to escape pervasive poverty and violence – comes as Secretary of State Mike Pompeo heads to Central America to discuss the issue. “I am watching the Democrat Party led (because they want Open Borders and existing weak laws) assault on our country by Guatemala, Honduras and El Salvador, whose leaders are doing little to stop this large flow of people, INCLUDING MANY CRIMINALS, from entering Mexico to U.S.,” Trump tweeted Thursday morning.