The US President has threatened to close the border with Mexico next week.
He warned that if authorities south of the border don't take action, he is willing to shut part or all of the border in response.
His comments come after the US Customs and Border Protection Commissioner Kevin K McAleenan claimed his officials had an "unprecedented" number of migrants in custody earlier this week.
President Trump issued his border warning in a series of tweets on Friday, arguing that closing the border "would be a good thing".
He claimed Mexico has "the strongest" immigration laws in the world while the US has "the weakest".
He threatened to close the border next week unless Mexico "immediately [stops] all illegal immigration" coming into the US.
Speaking to reporters in Florida, President Trump added: "We have the weakest, most pathetic [immigration] laws."
Calling on Congress and Mexico to take measures to halt illegal immigration, he added: "If they don't stop 'em, we're closing the border.
"We'll keep it closed for a long time - I'm not playing games."
Trump has already declared a national emergency at the border in a move to bypass Congress and secure funding for his controversial border wall.
Democrats, meanwhile, yesterday accused the Trump administration of creating "senseless heartbreak and horror at the border".
In a statement, House Speaker Nancy Pelosi claimed the administration are attempting to "fully revive" the practice of family separation and incarceration at the border.
.@realDonaldTrump’s failed policies have created senseless heartbreak and horror at the border – and dishonoring our values by hurting traumatized children & tearing apart vulnerable families does nothing to solve the situation he has caused. https://t.co/i1bVak2zJe pic.twitter.com/FeNeOLTedm
— Nancy Pelosi (@SpeakerPelosi) March 29, 2019