WATCH: Rand Paul ignites clash at Senate hearing by suggesting Ukraine is 'part of Russia'

Secretary of state Tony Blinken and Sen. Rand Paul (R-KY) clashed during a Senate Foreign Relations Committee hearing.

The Kentucky Republican agreed there was no justification for Russia's invasion of Ukraine, but he expressed strong opposition to Ukraine joining NATO because he said that would commit U.S. troops to the war.

"We have not had advocacy for U.S. troops because they are not part of NATO," Paul said. "Had they been or are they to become part of NATO, that means U.S. soldiers will be fighting in Ukraine and that is something I very much oppose."

Blinken told the senator that his judgment of the situation was different.

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"If you look at the countries Russia has attacked over the last years, Georgia, leaving forces in Moldova and repeatedly Ukraine, these are countries not part of NATO," Blinken said. "They do not attack NATO countries for probably good reason."

Then Paul, who the late Sen. John McCain accused in 2017 of "working for Vladimir Putin," responded with what appeared to be Russian talking points.

"You could also argue the countries they attacked were part of Russia, were part of the Soviet Union," Paul said.

The secretary of state said he firmly disagreed, saying those countries had a right to determine their own future, and Paul repeated his claim.

"I'm not saying it's not, but I'm saying the countries that have been attacked, Georgia and Ukraine, were part of the Soviet Union, they were part of the Soviet Union since the 1920s," Paul said.