Donald Trump defended his proposal for a new wall on the southern border of the United States, blasting the former Mexican president for rebutting the idea that Mexico would pay for the wall.

"The wall just got 10 feet taller, believe me," Trump said at tonight's Republican debate in Houston. "It just got 10 feet taller."

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.

"I don't mind trade wars when we're losing $58 billion a year, you want to know the truth," he said. "We're losing so much."