Trump shows off border wall in San Diego

During a visit to the border wall in San Diego, California, U.S. President Donald Trump said that if Mexico stopped helping to stem the flow of migrants, imposing tariffs on Mexican imports would be considered.

"We think we can get it close to 500 miles by the end of next year... we're building it at a breakneck speed," said Trump on Wednesday (September 18).

Earlier this year, Trump declared a national emergency in a bid to fund his promised wall at the U.S.-Mexico border.

On Wednesday, Trump said there was still a national emergency with regard to border security.