U.S. President Donald Trump Thursday discounted cryptocurrencies, including Bitcoin, and Facebook’s Libra digital coin.

He tweeted that companies should abide by the U.S. and global regulations and seek a banking charter if they want to “become a bank.”

He said, “I am not a fan of Bitcoin and other cryptocurrencies, which are not money, and whose value is highly volatile on thin air.”

He said if Facebook and other companies want to become a bank, they must seek a new Banking Charter and become subject to all banking regulations, just like other banks, both national and international,” he added.

His comment came out after Facebook last month said it would launch in Libra global cryptocurrency next year. Facebook and 28 partners, including Uber, Paypal, Mastercard, would form the association to govern the Libra.

Trump’s statement also came after Federal Reserve Board Chairman Jereme Powel said Facebook’s plan to create Libra could not move forward unless it removes concerns over privacy, money laundering, consumer protection, and financial stability.

The United States would not sit idle once cryptocurrencies like Libra seeks to replace the U.S. dollar as the key reserve currency.