President Donald Trump says he plans to double existing U.S. tariffs on foreign steel and aluminum from 25% to 50%, as other levies from the White House continue to face challenges in federal court.

In a May 30 post to his Truth Social platform, Trump said that U.S. steel and aluminum tariffs will increase, starting on June 4, in what he labeled as a "jolt" to domestic manufacturing. During remarks delivered at a U.S. Steel plant in Pennsylvania earlier that day, Trump also expressed his support for a controversial merger with Japan's Nippon Steel, according to CNBC, claiming that the deal won't result in layoffs, and that Nippon would commit to investing $14 billion over 14 months in U.S. Steel. 

Whether Trump will follow through on the threat remains a question, as investors on Wall Street have become increasingly skeptical of the White House's willingness to move forward with promised trade policies. That recently culminated in the creation of the "TACO" acronym (Trump Always Chickens Out) coined by Financial Times columnist Robert Armstrong, who asserted that the Trump administration has been "quick to back off" when threatened tariffs cause financial markets to spiral.

Trump's tariffs also came under fire in court on May 28, when the U.S. Court of International Trade (USCIT) ordered a halt to the administration's so-called "Liberation Day" levies, ruling that the White House does not have the authority to impose the duties using emergency powers. Less than a day later, a U.S. federal appeals court ruled that the President's tariffs could remain in place while the case plays out, although aluminum and steel tariffs were not impacted by the USCIT's initial ruling, given that they were implemented under the Commerce Department's authority to address perceived threats to national security.

In the meantime, the Trump administration is pushing to bring China back to the table to negotiate on a trade deal, with one official telling Bloomberg that the hope is to have Trump and Chinese President Xi Jinping engage in talks sometime in early June. On May 30, Trump accused China of violating the preliminary trade deal the two sides had agreed to as part of a 90-day pause on reciprocal tariffs. China refuted that claim on June 2, instead accusing the U.S. of violating the agreement, as the Trump administration has tightened export restrictions on semiconductor software to China, and announced plans to revoke visas for Chinese students, CNBC reports.