U.S. Treasury Secretary Steven Mnuchin says U.S. sanctions on Russian oligarchs that sent the ruble tumbling and roiled metals markets had the effect the Trump administration wanted.

Speaking in an interview broadcast Thursday on Fox Business, he said that the sanctions against tycoons close to the Russian government had the "necessary impact," Bloomberg wrote.

However, he didn't rule out additional financial penalties, saying the administration "is not afraid to use these tools – we will use these tools – but we're not going to broadcast to the world our exact thinking."

Read alsoWP: Trump puts the brakes on new Russian sanctions, reversing Haley's announcementAs was earlier reported, the United States imposed new sanctions against Russia on April 6. The list included such oligarchs as Oleg Deripaska, Igor Rotenberg, Suleiman Kerimov, Igor Rotenberg, and Kirill Shamalov, as well Gazprom's chief executive Alexei Miller, Russian Security Council Secretary Nikolai Patrushev, and Roskomnadzor head Alexander Zharov. Moreover, sanctions were introduced against 15 Russian companies.