Donald Trump has mocked Mexico throughout his campaign, so today's "private" visit to the Presidential Palace came as a surprise. Trump may have little to lose but, for Enrique Peña Nieto, it could be another story. Mexico's former President, Vicente Fox, called Nieto's invitation "an enormous political risk…. he could even be perceived as a traitor. Hillary Clinton held forth on Trump's trip before he'd even arrived in Mexico, "It certainly takes more than just making up for a year of insults and insinuations by flying in on our neighbor and then flying out a couple hours later… that's not how it works." Andrew Selee specializes in Mexico. He's Vice President of the Woodrow Wilson Center in Washington.