Florida Sen. Marco Rubio is warning the Trump administration that its new efforts to partner with Russia on a "Cyber Security unit" to protect U.S. elections won't work.

In a series of tweets that came after President Trump's own messages on Twitter, the Republican likened a potential partnership with Russia to cooperating with Syrian President Bashar Assad to reduce chemical weapons.

"While reality & pragmatism requires that we engage Vladimir Putin, he will never be a trusted ally or a reliable constructive partner," Rubio said Sunday.

"Partnering with Putin on a 'Cyber Security Unit' is akin to partnering with Assad on a 'Chemical Weapons Unit.' We have no quarrel with Russia or the Russian people. Problem is with Putin & his oppression, war crimes & interference in our elections."

Moments before Rubio's tweets, Trump had remarked on Twitter about his meeting with Putin in Hamburg, Germany, last week during the G-20 summit .

He said Putin denied Russia interfered in the U.S. election and they "discussed forming an impenetrable Cyber Security unit so that election hacking, & many other negative things, will be guarded and safe."