"So we will put tariffs if they don't apprehend (migrants) and ultimately - we're going to give a period of time, but if in a year from now if drugs continue to pour in, we're going to put tariffs on them", he said.
Trump's new border policy was first announced in a confusing statement to journalists at a White House meeting on the completely unconnected subject of USA urban renewal.
"I'll do it", he said.
"If Mexico doesn't give the help, that's OK, we're going to tariff their cars", Trump said at the White House.
CBP El Centro Sector chief Gloria Chavez presented Trump with a segment of the newly built border barrier, as a symbol that the "wall works".
"If they don´t, we´re going to tariff their cars at 25 percent coming into the United States", he said.
President Donald Trump denied Friday he changed his mind about closing the U.S. -Mexico border, one day after apparently backtracking on the threat if Mexico does not act to halt the flow of illegal immigrants and drugs from entering the U.S.
Press Secretary Sarah Huckabee Sanders said Thursday he will be briefed by U.S. Customs and Border Protection officials on "exactly what is taking place at the border".
The president has said the administration is making progress in building a border wall and says he expects "close to 400 miles" to be completed within the next two years.
Mr Trump traveled today to Southern California to meet with local law enforcement officials and tour a section of recently rebuilt fencing he cites as the answer to a surge of migrant families coming to the U.S. in recent months.
Jesus Seade, the Mexican undersecretary for North America, also brushed off the threat of new tariffs, saying officials were "not concerned" and noting the tariffs are not part of the United States-Mexico-Canada Trade Agreement that the countries have agreed to but not yet ratified. Mexico is the third largest U.S. trading partner and any hold ups at the border crossings would have an immediate impact on trade. Most are Central American families seeking asylum.
Tariffs do squeeze the manufacturers who export to the USA from foreign countries by making their products more expensive in the United States. The governor issued the strong criticism in a statement Friday as the president arrived in California to visit the U.S. -Mexico border. Arrests along the southern border have skyrocketed in recent months and border agents were on track to make 100,000 arrests or denials of entry in March, a 12-year high.
"Democrats haven't offered a shred of evidence to suggest that the IRS hasn't done its job auditing President Trump's taxes or anybody else's for that matter", said Grassley, who has said in the past that he wants his committee to receive the returns as well if Neal receives them.
Trump has invoked other executive powers, including declaring a national emergency in an effort to secure more money for his long-promised border wall.
The Democratic-controlled U.S. House of Representatives, meantime, will sue to prevent Trump's transfer of money to pay for the wall, Speaker Nancy Pelosi said Thursday. Congress voted to block the emergency declaration, but Trump vetoed that measure.