Updated at 3:01 p.m. ET
New tariffs against Mexico will begin to bite next week, President Trump vowed Tuesday, unless the White House is satisfied that Mexico's government is acting with new alacrity to stop migrants from crossing into the United States.
"This will take effect next week, 5%," Trump said during his visit to London.
Trump said he is open to continuing negotiations with Mexican leaders, including at a meeting scheduled for Wednesday between its foreign minister and Secretary of State Mike Pompeo.