In a move to curb illegal immigration, United States President Donald Trump has announced tariffs on all goods coming from Mexico.
In a tweet, Trump said that from 10 June a 5% tariff would be imposed and would slowly rise "until the Illegal Immigration problem is remedied".
President Trump has declared a national emergency to tackle what he claims is a crisis at the US southern border.
Border agents say they are overwhelmed, but critics say they are mishandling and mistreating migrants.
Jesus Seade, Mexico's top diplomat for North America, said the tariffs would be "disastrous".
"If this is put in place, we must respond vigorously," he told reporters.
In a White House statement, Mr Trump said the tariffs would rise by 5% each month until October 1, when the rate would reach 25%.
The tariffs would stay at that level "unless and until Mexico substantially stops the illegal inflow of aliens coming through its territory", he said.
"For years, Mexico has not treated us fairly - but we are now asserting our rights as a sovereign Nation," the statement said.