Kerry Says Mexico Won't Pay for Wall and Not to Do Diplomacy by Tweet

Secretary Kerry sat down for an interview with ABC News.

— -- Disputing the feasibility of one of President-elect Donald Trump's best-known campaign promises, outgoing Secretary of State John Kerry said today he doesn't think Mexico will pay for a border wall.

"They’re not going to voluntarily pony up and pay for something they disagree with," Kerry told ABC News' Martha Raddatz in an interview at the Department of State.

Trump said repeatedly during his campaign that he wanted to build a wall between the U.S. and Mexico and that Mexico would pay for it. Mexico's President Enrique Pena Nieto has said the country would not do so.

Trump's incoming press secretary, Sean Spicer, said on "Good Morning America" today that Trump is working with Republicans in Congress to appropriate funding to build the wall and that the administration will find a way, "whether it's through higher tariffs or a direct check," to get Mexico to reimburse the U.S. for the costs.

Trump tweeted this morning that the media are dishonest for failing to report that Mexico will pay for wall at a later date.

Kerry also commented on Trump's discussion of policy on Twitter, telling Raddatz that he doesn't think the social media platform is an appropriate forum for discussing U.S. foreign policy.

"I don't make announcements of foreign policy by tweet, Twitter. I don't think that, you know, 140 characters allows you to adequately deal with the complexity of many of the choices that we make," Kerry said.

He said he doesn't want to engage in back-and-forth with Trump and his team on the issue but hopes that they decide to "move to a different way of communicating."

Trump tweets almost daily on topics as mundane as reality television and as serious and geopolitically sensitive as tensions between China and Taiwan.

After Trump won the election, he rattled diplomats and broke with U.S. policy by accepting a phone call from the president of Taiwan — which led to a formal protest by the Chinese government. Beijing claims Taiwan as part of China, and the U.S. has tread carefully by recognizing China's policy while maintaining separate relations with Taiwan.