'Good luck': Obama mocks Trump's 'half-baked' plan to make Mexico pay for a massive US border wall
"Good luck with that," Obama said sarcastically.
He took a question about Trump's plan after announcing his support for tax reform amid the bombshell Panama Papers documents leak.
Earlier in the day, The Washington Post reported that Trump's campaign had finally laid out the methods he planned to use to force Mexico into paying for a US border wall.
In a campaign memo, Trump vowed to restrict money transfers to Mexico unless the country made a one-time payment of $5 billion to $10 billion for the wall. Those transfers, known as remittance payments, are often from immigrants who are sending money home to family members in Mexico.
But Obama said the consequences of Trump's proposal would be "enormous" and "impractical." He also said it would require tracking "every Western Union bit of money being sent back to Mexico."
"Then we've got the implications for the Mexican economy, which in turn if it's collapsing, sends more people north because they can't find jobs there," Obama said. "This is something that's not thought through."
Obama further said he was "constantly" being asked by foreign leaders about "some of the wackier" foreign-policy suggestions made by Trump.
"They don't expect half-baked notions coming out of the White House," Obama said. "We can't afford that."
For their part, Mexican leaders have previously flatly rejected Trump's notion that their country would pay for the wall along the border.
Obama's latest critique of Trump came after he took shots at the business mogul's foreign policy on Friday, not long after Trump told The New York Times that he would be open to a nuclear-capable Japan and South Korea in exchange for an ease in security commitments for the US.
"They tell us that the person who made the statements doesn't know much about foreign policy or nuclear policy or the Korean Peninsula or the world, generally," Obama said during the news conference, which came at the conclusion of the Nuclear Security Summit. The Summit was attended by various world leaders in Washington, D.C.