Trump is warning a caravan of migrants that the US military is waiting for them as 5,000 more troops head to the border

• President Donald Trump warned the "caravan of migrants" approaching the US-Mexico border Monday that the US military will be waiting for them when they arrive.
• He characterized their march as an "invasion," a term he has used in the past.
• His warning comes as the US military is reportedly preparing to send 5,000 troops to the border, a significant increase over the initial estimates of 800 reported last week.
• The deployment would mean that there would be more troops serving at the border than there are in Iraq and Syria.

The US military, at the urging of the White House, plans to send 5,000 troops to the southern border to support the thousands of National Guard personnel and customs officials already there, The Wall Street Journal reported Monday.

The troops, which are expected to initially be stationed at ports of entry, will be deployed to provide additional security as the so-called "caravan of migrants" pushes toward the US-Mexico border. The plan, known as Operation Faithful Patriot, will see 1,800 troops sent to Texas, 1,700 to Arizona, and 1,500 to California.

The figure reported Monday is a marked increase over the initial estimates of 800 troops reported last week. The troops expected to be sent to the border will primarily consist of military police and engineers, but the military also reportedly plans to send Marines.

"On the border, we are preparing what we call Defense Support for Civilian Authorities,'" Secretary of Defense Jim Mattis said Sunday, "If you look at how we organize for the storms, ... we surround the storm."

"Right now, we're planning it, how we're going to do it," he added.

A Pentagon spokesperson told the WSJ that any reporting on troop deployment figures is "premature," as planning is still underway, but some US troops are reportedly already on their way to the border, where they are expected to serve until mid-December.

President Donald Trump has been tweeting repeatedly about the caravan, calling significant attention to it ahead of the mid-term elections.

"Please go back," the president tweeted Monday. "This is an invasion of our Country and our Military is waiting for you!"