President Donald Trump signed an executive order on Tuesday that launched a national security investigation into the U.S. reliance on imports of critical minerals, after China suspended exports of certain rare earth metals and magnets.

In a Tuesday social media post, President Donald Trump claimed he will protect farmers and said he recognizes he had to support them financially during his first administration after they were hit by a trade war with China.

Trump on April 2 stunned the world with massive tariffs that he said would prevent countries like China from “ripping off” the U.S. Chinese leader Xi Jinping ditched official caution and issued a patriotic message casting doubt on whether American voters could bear as much hardship as the Chinese.