President Donald Trump threatened Thursday to send the military to block the migrant caravan heading for the United States border.

“I must, in the strongest of terms, ask Mexico to stop this onslaught – and if unable to do so I will call up the U.S. Military and CLOSE OUR SOUTHERN BORDER!” Trump wrote on Twitter.

The caravan of migrants that began in Honduras has grown to several thousand people after passing into Guatemala as it heads for the Mexican border. Other Hondurans are leaving the country to join it.

Trump threatened to stop all federal payments to Guatemala, Honduras, and El Salvador if the countries failed to block the flow and blamed Democrats for rejecting a reform of immigration laws allowing them to claim asylum. He also claimed that the caravan included criminals.

“Hopefully Mexico will stop this onslaught at their Northern Border,” he wrote. “All Democrats fault for weak laws!”

Trump appeared willing to end his new trade deal with Mexico if the caravan was not stopped.

“The assault on our country at our Southern Border, including the Criminal elements and DRUGS pouring in, is far more important to me, as President, than Trade or the USMCA,” he wrote.

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….. — Donald J. Trump (@realDonaldTrump) October 18, 2018

….In addition to stopping all payments to these countries, which seem to have almost no control over their population, I must, in the strongest of terms, ask Mexico to stop this onslaught – and if unable to do so I will call up the U.S. Military and CLOSE OUR SOUTHERN BORDER!.. — Donald J. Trump (@realDonaldTrump) October 18, 2018