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Republican Senator Ted Cruz on Thursday said Russia is invading Ukraine “because of enormous mistakes that the Biden administration has made.”

“What we’re seeing right now is the most serious military conflict in Europe since World War II,” Cruz told CBS News chief election and campaign correspondent Robert Costa on Thursday. “It is devastating, and unfortunately, I expect it’s likely to get worse before it gets better. What is frustrating is that what is happening right now was entirely avoidable. The reason that Russia is invading Ukraine is because of enormous mistakes that the Biden administration has made, and two in particular.”

In particular, Cruz, who was interviewed by Costa at the Conservative Political Action Conference in Florida,  blamed the president’s decision to withdraw U.S. troops from Afghanistan last summer, claiming it made the Oval Office look weak to America’s enemies. He also pointed to the president’s earlier decision to waive sanctions on the Nord Stream 2 pipeline that would bring natural gas from Russia to Germany. Russia has long wanted to remake the old Soviet Union, but Cruz argued recent Biden administration actions have made that dream easier. 

“President Biden made a political decision to surrender to Putin, to waive sanctions on the Nord Stream 2 pipeline, which is what has facilitated this invasion,” he said. 

Mr. Biden lifted sanctions on Nord Stream 2 last year, and Cruz placed a hold on the president’s State Department nominees until this week, when the president imposed sanctions on the company constructing the pipeline and its leadership. Germany announced it would halt Nord Stream 2 earlier this week, amid heavy international pressure, but Cruz argued Russia needs to hear with certainty the pipeline will never be used. 

“The way to stop the invasion is for Russia to believe that they will not be able to get their gas to Europe if they continue this invasion. And the only way to do that is impose the sanctions, and Joe Biden just did that, finally, but now the problem is Putin doesn’t believe those sanctions will stay,” Cruz said. 

Still, “there may be nothing” that stops Putin’s invasion at this point,” Cruz said. 

Moving forward, Cruz said sanctions “should include every tool we have,” and he added that “under no circumstances should American troops be fighting Russians in Ukraine.”

Given the chance, Cruz declined to directly criticize Trump’s comments about Putin and Russia in recent days. Trump called Putin “smart” in a radio interview with “The Clay Travis & Buck Sexton Show” on Tuesday, after the Russian president gave a speech that laid out his justification for Russia’s move into Ukraine. “I said, ‘This is genius.’ Putin declares a big portion of the Ukraine of Ukraine. Putin declares it as independent. Oh, that’s wonderful. So Putin is now saying it’s independent, a large section of Ukraine. I said, ‘How smart is that?’ And he’s going to go in and be a peacekeeper.” 

“His rhetoric I, with some regularity disagree with,” Cruz said of Trump, but added that when it comes to Russia-related policy, Trump was superior to Mr. Biden.