Former Mexican president Vicente Fox had said the country is "not going to pay for that f****** wall."
Trump took direct aim at Fox's language, despite his own personal use of profanity. "I can only tell you, if I would have used even half of that word, it would have been national scandal," he said. "This guy used a filthy, disgusting word on television and he should be ashamed of himself and he should apologize."
He then blasted his GOP rivals over funding for the wall. "Now, the wall is $10 billion to $12 billion, if I do it," he claimed. "If these guys do it, it will end up costing $200 billion."
Trump has not released any specific plans for funding or building the wall.
When asked whether he would be willing to start a trade war with Mexico over building the war, Trump said he would.