NEW YORK -- US President Donald Trump announced Saturday morning that 30 percent tariffs will be imposed on the European Union (EU) and Mexico as of Aug 1.

The new tariffs were announced in the letters addressed to European Commission President Ursula von der Leyen and Mexican President Claudia Sheinbaum and posted on Trump's social media platform Truth Social.

Trump criticized Mexico for its "failure to stop the cartels" from smuggling drugs, including fentanyl, into the United States, and accused the country of not doing enough to cooperate with Washington in curbing illegal immigration.

In the case of the EU, the US president scolded the bloc for its tariff and non-tariff barriers, which he blamed for causing "long-term, large, and persistent Trade Deficits."

"Our relationship has been, unfortunately, far from reciprocal," he wrote in the letter.

Trump used largely the same wording in his letter as in those sent earlier this week to leaders of other countries, warning them not to retaliate, urging them to relocate companies to the United States, and suggesting that the tariff rates could be adjusted if they cooperate.

Trump has sent more than 20 similar letters to other US trading partners in the past week, including Canada, South Korea, Japan and Brazil, with blanket tariff rates ranging from 20 percent up to 50 percent.

Von der Leyen quickly responded to Trump's announcement, saying they are open to trade talks with the US for an agreement before the deadline, but won't rule out taking countermeasures.

"We remain ready to continue working towards an agreement by Aug 1," the EU leader said in a statement, "At the same time, we will take all necessary steps to safeguard EU interests, including the adoption of proportionate countermeasures if required."

"Imposing 30 percent tariffs on EU exports would disrupt essential transatlantic supply chains," she said, "We continue to deepen our global partnerships, firmly anchored in the principles of rules-based international trade."

A joint statement by the Mexican economy and foreign ministries accused the tariffs of "unfair treatment," saying the country is "already in negotiations with the US" to avoid tariffs going into effect on Aug 1.