Bill Ackman, founder and CEO of Pershing Square Capital Management.

Adam Jeffery | CNBC

Investor Bill Ackman said Monday it’s time for the U.S. to consider military intervention in defense of Ukraine as Russian forces continue to advance into the country from multiple directions.

In a series of tweets to more than 400,000 followers, the founder and CEO of Pershing Square Capital Management urged President Joe Biden to start considering taking actions beyond economic sanctions if the conflict doesn’t resolve.

“I hope Russia stops this onslaught, but I don’t see how Putin saves face. We need to be prepared for what comes next which means we need to start thinking about intervening military,” Ackman said in the Twitter thread. “Isn’t it time we set a real red line?”

“We can’t sit back and allow hundreds of thousands of Ukrainians and perhaps millions to die. I don’t want to live in that world and you don’t either. @POTUS, it is in your hands. You can fix the errors of the past and protect our future. With all due respect Mr. President, the time is now,” Ackman said.

The Biden administration has announced sanctions against Russia’s central bank, the National Wealth Fund of the Russian Federation and Russia’s Ministry of Finance, moves that effectively prohibit Americans from doing any business with the entities. The action will also freeze any assets within the United States.

In the latest development, a Ukrainian delegation has arrived near the border with Belarus to hold talks with Russian officials. Ukraine’s armed forces continue to hold off Russian troops, defending and retaining control of key cities, and slowing Russia’s advance on Kyiv.

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