Washington (CNN) President Donald Trump backpedaled on his threat to shut down the southern border, saying Thursday that now he doesn't think the US will "ever have to close the border."

Trump, earlier Thursday, threatened to slap tariffs on automobiles made in Mexico and close the US-Mexico border if the country didn't stop "massive amounts of drugs" coming into the US within one year.

"We're going to give them a one-year warning, and if the drugs don't stop or (are) largely stopped, we're going to put tariffs on Mexico and products, in particular, the cars ... and if that doesn't stop the drugs, we close the border," Trump told reporters.

But by Thursday evening, Trump had shifted his position again.

"I don't think we'll ever have to close the border because the penalty of tariffs on cars coming into the United States from Mexico, at 25%, will be massive," Trump said.

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