Secretary of State Antony Blinken said Sunday that the U.S. has seen “more cracks emerge in the Russian facade” after mercenary chief Yevgeny Prigozhin posed a “direct challenge to Putin’s authority” in his rebellion against Moscow’s military.

Following an armed revolt against Russia’s military leaders that lasted less than 36 hours, Prigozhin, the head of the Wagner mercenary group that had long been at odds with Vladimir Putin’s forces, on Saturday ordered his troops to turn back from their march on Moscow, abandoning their rebellion to avoid bloodshed.

In an interview on NBC News’ “Meet the Press,” Blinken said that “what we’ve seen is Russia having to defend Moscow, its capital, against mercenaries of its own making,” adding that “in and of itself, that’s extraordinary.”

“We’ve also seen rise to the surface profound questions about the very premises for this Russian aggression against Ukraine that Prigozhin surfaced very publicly, as well as a direct challenge to Putin’s authority,” he said.

Blinken added: “So I think we’ve seen more cracks emerge in the the Russian facade. It is too soon to tell exactly where they go, and when they get there, but certainly we have all sorts of new questions that Putin is going to have to address in the weeks and months ahead.”

Pressed on reports that Belarusian President Alexander Lukashenko helped broker a deal between Prigozhin and Putin, Blinken stressed that it’s important not to speculate on the details and signaled that more information on the agreement will trickle out in the coming days and weeks.

“It may be that Putin didn’t want to debase himself to the level of negotiating directly with Prigozhin,” he said. “So it was useful to get someone like Lukashenko into this on his behalf.

Summer Concepcion

Summer Concepcion is a politics reporter for NBC News.

Christina Zhao contributed.