Facebook CEO Mark Zuckerberg told lawmakers that the social media giant will not “be a part of launching the Libra payments system anywhere in the world” unless U.S. regulators give the green light.

In a testimony submitted to the House Financial Service Committee today, Zuckerberg addressed several concerns policymakers have expressed regarding Facebook’s blockchain project. He also said that Facebook supports “Libra delaying its launch until it has fully addressed US regulatory concerns.”

Zuckerberg emphasized that Libra is not intended to compete with sovereign currencies. Instead, the Libra Association will work with the Federal Reserve and other central banks to make sure it does not interfere with monetary policies, he said.