President Donald Trump said Tuesday he’s imposing a new 50% tariff on all copper. However, it’s unclear when the new tariff would take effect.

U.S. President Donald Trump indicated a sweeping 50% tariff on all copper imports into the country, significantly escalating ongoing global trade tensions. The 50% copper tariff will likely take effect at the end of July or on August 1.

The Yale Budget Lab noted that the letters sent Monday would hike the effective tariff rate on U.S. consumers to the highest since 1934.