Russia is temporarily limiting exports of enriched uranium to the U.S., creating potential supply risks to utilities operating American reactors that generate almost a fifth of the nation’s electricity.

The Russian government didn’t provide details regarding the restrictions or their duration in a Friday statement on Telegram. Utilities tend to make purchases well in advance, so any impact is unlikely to be immediate.

As Russia’s prolonged war in Ukraine has made it increasingly unpopular on the world stage, the nation has repeatedly signaled a willingness to use its vast energy resources as geopolitical bargaining chips. Russia also told Austria on Friday that it’s throttling gas supplies, interrupting a six-decade supply agreement currently covering 80% of demand because of a legal dispute.