Washington (CNN) President Donald Trump on Monday once again insisted that Mexico will pay for a southern border wall, while still raising the specter of a government shutdown over funding for it.

"One way or the other, Mexico is going to pay for the wall," Trump said Monday.

But pressed as to why he floated the possibility of a government shutdown if Congress refused to provide funding for the border wall, Trump again stressed the need for Congress to provide funding for it.

"I hope that's not necessary. If it's necessary, we'll have to see," Trump said of a possible government shutdown. "The wall is needed from the standpoint of security."

Mexico has been adamant that it will not help fund a border wall between the two countries, but Trump said that he would eventually compel Mexico to pay for the wall through indirect mechanisms, such as a form of reimbursement.

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