Donald Trump vowed Wednesday to forge ahead with plans for a wall on the southern US border after taking office, and said Mexico would reimburse the United States for the cost.

"I could wait about a year and a half until we finish our negotiations with Mexico, which we'll start immediately after we get to office, but I don't want to wait," Trump told a news conference.

"We're going to start building," he said. "Mexico in some form -- and there are many different forms -- will reimburse us and they will reimburse us for the cost of the wall." 

"That will happen. Whether it's a tax or whether it's a payment."