He also accused US House of Representatives Speaker Nancy Pelosi of being very rigid and doing bad politics.
"I think that she was very rigid which I would expect but I think she's very bad for our country. She knows that you need a barrier, she knows we need border security. Basically, she wants open borders, she does not mind human trafficking," he said as he accused Pelosi of doing very bad politics.
Pelosi, by her stand against the wall, is costing the country hundreds of billions of dollars, Trump said.
"She is doing a terrible disservice to our country," the US president said.
In the interview, as reported by CBS News, he said that negotiations with the opposition Democrats which started after the government shutdown ended are a waste of time.
"We will be looking at a national emergency, because I don't think anything is going to happen. I think the Democrats don't want border security. And when I hear them talking about the fact that walls are immoral and walls don't work -- they know they work," he told reporters earlier in the day.
Trump insisted that he is building the wall and will continue building it, as this is the only way to stop the flow of illegal immigrants into the country.
"I think there's a good chance that we'll have to do that. But we will, at the same time, be building - regardless, we're building wall and we're building a lot of wall. But I can do it a lot faster the other way," the president said.
Claiming that there are three caravans heading towards the US, he said if there was a wall, it would not even be a problem.
"But we've sent 2,500 military down to help Border Patrol and law enforcement. I have to say, the military has done an incredible job, including helping us with some walls and some fences, which are very nice to say.
"Unsecure borders give traffickers free and clear passage to transport their victims into the United States. It's a tremendously big money-maker for some very, very bad people," Trump said.
Meanwhile, Pelosi's office accused Trump of making reckless remarks.
"President Trump's recklessness didn't make us safer, it undermined our security with 35 days of border patrol agents, Drug Enforcement Administration agents, FBI agents and Homeland Security personnel missing paychecks," said Drew Hammill, her spokesman.
"Democrats have put forward strong, smart and effective border security solutions in the bipartisan conference committee, while the President still refuses to take a second shutdown off the table.
"The President's wild and predictable misrepresentations about Democrats' commitment to border security do nothing to make our country safer," she said.
Trump, addressing reporters at the White House, said: "Nancy Pelosi is doing a very, very great disservice to our country. I think she's got to get on the ball, because we're going to have a wall that's being built anyway.
"But if you don't have it - human trafficking, just as an example. When you see today what's going on, people that aren't willing to do what they have to do, and they know what they have to do, they're doing the country a tremendous disservice".
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