European Union (EU) leaders said over the weekend that they will not accept an increase in U.S. tariffs in the wake of a Supreme Court ruling against some of President Trump’s most sweeping tariffs.

“The Commission will always ensure that the interests of the European Union are fully protected. EU companies and exporters must have fair treatment, predictability, and legal certainty,” the European Commission said in a Saturday statement.

“A deal is a deal. As the United States’ largest trading partner, the EU expects the U.S. to honour its commitments set out in the Joint Statement – just as the EU stands by its commitments,” the commission added, referencing a deal struck between the U.S. and EU last summer.

Trump and Commission President Ursula von der Leyen announced a trade deal last July setting tariffs at 15 percent for European goods. The deal also includes the EU purchasing $750 billion worth of energy from the U.S.

The agreement was notably lower than a 30-percent tariff the president had threatened for the EU and avoided a trade war between the EU and U.S.

The Supreme Court on Friday rejected most of Trump’s expansive tariffs, a hallmark of his administration’s economic strategy. Throughout his presidency, the president’s tariff policy has rattled global markets, increased economic uncertainty and strained relationships with longtime American allies including the EU and Canada.

Friday’s 6-3 decision struck down the president’s expanded use of the International Emergency Economic Powers Act for imposing tariffs on almost every country. The law, from the 1970s, lets the president “regulate” imports when needed in response to national emergencies that pose an “unusual and extraordinary” threat.

On Saturday, Trump announced he was raising a newly imposed global tariff to 15 percent after reviewing the Supreme Court’s decision.

One day later, European Central Bank President Christine Lagarde said countries need “clarity” on the future of their trade relationships with the United States.

When reached for comment, the White House directed The Hill to a post from Trump in which he said that “Any Country that wants to ‘play games’ with the ridiculous supreme court decision, especially those that have ‘Ripped Off’ the U.S.A. for years, and even decades, will be met with a much higher Tariff, and worse, than that which they just recently agreed to.”