(CNN) President Donald Trump claimed Thursday that his oft-made 2016 campaign promise that he would build a wall and Mexico would pay for it didn't mean it would be a direct payment, despite outlining just that scenario during his campaign.

"When during the campaign, I would say 'Mexico is going to pay for it,' obviously, I never said this, and I never meant they're gonna write out a check, I said they're going to pay for it. They are," he said as he prepared to depart the White House for the southern border.

"It's an easy decision for Mexico: make a one-time payment of $5-10 billion to ensure that $24 billion continues to flow into their country year after year," the memo said.

Using a broad interpretation of the post-9/11 USA Patriot Act, Trump wrote in the memo that he would threaten to issue new regulations that would compel money transfer companies like Western Union to verify a client's identity and legal status before authorizing a wire transfer.

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