Sen. Rand Paul (R-Ky.) took to Facebook this afternoon to hit back at his Republican colleague Marco Rubio, who said last night that Paul "doesn't know what he's talking about" when it comes to U.S.-Cuba relations.

Paul appeared to support President Obama's decision to normalize relations with Cuba on Wednesday, saying the "50-year embargo with Cuba just hasn't worked."

Rubio fired back, telling Megyn Kelly, that “like many people that have been opining, [Paul] has no idea what he’s talking about."

He argued that the embargo is full of "holes," and said the brutal dictatorship is the cause of Cuba's problems, not the embargo.

Writing on Facebook today, Paul asked why the United States should not try a "new approach" when it comes to dealing with the Communist regime.

On "The Kelly File" last night, Paul said that he never starts a fight, but he's happy to finish one.

He characterized Rubio's comments as "rude" and "intemperate" and asserted that opening up relations with Cuba is a good idea.

"If the embargo's full of holes and doesn't work, why does [Rubio] want to keep it so much? Why do we want to keep something that's not working?"

He said that trade draws nations together and helps improve relations.

"We've had Cuban isolationism for 50 years - no trade, no diplomacy - and yet it hasn't worked."

As for his disagreement with Rubio, he said it's mainly about the issues, but also the rude and inappropriate language Rubio used.

"If someone's going to cast dispersions on me and not talk about policy, then there will be an altercation, and I won't shy away from a battle, and I think I've shown that."

Watch the full "Kelly File" interview with Sen. Rubio below and let us know your thoughts on the disagreement.