Donald Trump is not a fan of Libra, Facebook's proposed cryptocurrency, the president made clear in a series of tweets on Thursday evening.

"Facebook Libra’s 'virtual currency' will have little standing or dependability.," Trump tweeted. "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."

Trump is the latest—and most high-profile—public official to raise doubts Facebook's cryptocurrency plans. On Wednesday, Federal Reserve chairman Jerome Powell warned that "Libra raises many serious concerns regarding privacy, money laundering, consumer protection and financial stability."

Some members of Congress have also signaled skepticism, with one group of Democrats in the House calling on Facebook to suspend work on Libra while policymakers examine its implications.

For his part, Trump isn't just hostile toward Libra. In another Thursday tweet, he declared that he was "not a fan of Bitcoin and other Cryptocurrencies, which are not money, and whose value is highly volatile and based on thin air." He warned that "unregulated Crypto Assets can facilitate unlawful behavior, including drug trade and other illegal activity."

Trump framed his cryptocurrency skepticism in terms of economic nationalism.

"We have only one real currency in the USA, and it is stronger than ever, both dependable and reliable," Trump tweeted. "It is by far the most dominant currency anywhere in the world, and it will always stay that way. It is called the United States Dollar!"