United States President Donald Trump on Saturday said he is raising a new global tariff to 15 percent, less than a day after announcing a 10 percent worldwide duty following a U.S. Supreme Court ruling that struck down most of his previous levies.

Trump made the announcement on his social media platform, Truth Social, saying that as president he would raise the 10 percent worldwide tariff "to the fully allowed and legally tested 15 percent," adding that the measure would take immediate effect.

He said that over the next "short number of months," his administration will determine and issue new legally permissible tariffs, which he said will continue the United States' "extraordinarily successful process of Making America Great Again."

Section 122 of the U.S. Trade Act grants the president authority to impose tariffs of up to 15 percent for up to 150 days to address balance-of-payments issues.

Any extension beyond the 150-day period requires congressional approval.

The announcement came hours after Trump signed a proclamation to implement a global 10 percent tariff, following the Supreme Court's decision Friday to strike down his earlier, far-reaching global tariffs.