After boasting for months about its preferential trade deal with U.S. President Donald Trump, the U.K. is at risk of becoming the biggest loser in the aftermath of the U.S. Supreme Court¡¯s decision to strike down his global tariffs.

Britain had enjoyed a relatively lower reciprocal tariff rate of 10% compared with other countries ¡ª giving it a competitive advantage ¡ª but Trump¡¯s promise to reimpose the levies at 15% for all nations means businesses may now face even higher duties. The U.K. will see the largest increase as a result, followed by Italy and Singapore, according to Global Trade Alert, while Brazil, China and India stand to benefit the most.

¡°At the moment, we have no clarity on whether the 10% tariff agreed will be honored ¡ª but until and unless the U.S. gives a steer, we¡¯ve got to assume it¡¯s 15%,¡± said Sam Lowe, a trade specialist at strategic advisory firm Flint Global in London.