Donald Trump has suggested that US soldiers could open fire at the migrant caravans approaching America if they throw rocks.
During a live address from the White House, Mr Trump declined to rule out the possibility of troops deployed at the border shooting at people crossing into the country illegally.
Mr Trump said: “I hope there won’t be that, but I will tell you this – anybody throwing stones, rocks … we will consider that a firearm, because there’s not much difference.”
The comment, one of the starkest he has made to date about the caravans approaching America, increased fears that there could be clashes at the border.
It came as Mr Trump spoke from a podium in the White House for more than 20 minutes in an apparent attempt to amplify his message over border security ahead of Tuesday’s midterm elections.
Mr Trump said some of those migrants travelling through Central America had “overrun” the Mexican police and “badly hurt” some of that country’s soldiers.
Two Years of Trump
He said the caravans were “marching” towards the US southern border and were filled with “young, strong men” who “maybe we don’t want in our country”.
He also vowed to reform the asylum system, insisting migrants seeking such status would be made to wait at the border while their requests are processed.
“We will not allow our generosity to be abused by those who would break our laws, defy our rules, violate our borders [and] break into our country illegally,” Mr Trump said.
He said any migrants who do enter the country would be housed in "massive tent cities" he plans to build while their cases are processed. "We’re going to catch, we’re not going to release," he said.
Under current protocol, many asylum seekers are released while their cases make their way through backlogged courts – a process that can take years.
He later added: “This is a perilous situation and it threatens to become even more hazardous as our economy becomes better and better.”
The address, which was followed by a question and answer session with reporters, was carried live on CNN and Fox News.
The escalating warnings come as Mr Trump attempts to frame next week’s elections around border security, one of the central themes of his 2016 election victory.
The president is fighting to protect Republican majorities in the House of Representatives and Senate and appears to believe immigration is a topic that will drive his supporters to the polls.
Mr Trump defended his rhetoric in an interview with CBN, insisting that he was “not anti-immigrant at all” and favoured people coming into the country legally on the basis of merit.
“You know the word racist is used about every Republican that’s winning. Any time a Republican leading they take out the r-word, the racist word,” he said, rejecting criticism.
Mr Trump has given little ground amid outcry from political opponents and charities as he dialed up the strength of his warnings over illegal immigration as election day approaches.
The US president called those travelling in the caravans “no angels” in one TV interview and said: “They can’t invade our country. You look at that, it almost looks like an invasion.”
On the size of the caravans, Mr Trump said: “I’m pretty good at estimating crowd size and I’ll tell you they look a lot bigger than people would think.”
He also defended suggesting that up to 15,000 US troops could ultimately be sent to the border – more than are stationed in Afghanistan. By the end of the week at least 7,000 troops are expected to be in place.
And he has faced a backlash after tweeting a campaign video showing a convicted illegal migrant boasting about killing cops while in a court room.
Jeff Flake, the outgoing Republican senator for Arizona, said the advert was “sickening” and called on members of his party to “denounce” it.
Mr Trump had tweeted the video to his 51 million followers with the words: “It is outrageous what the Democrats are doing to our Country. Vote Republican now!”