Filmmaker Rob Reiner slammed President TrumpDonald John TrumpTrump calls Sri Lankan prime minister following church bombings Ex-Trump lawyer: Mueller knew Trump had to call investigation a 'witch hunt' for 'political reasons' The biggest challenge from the Mueller Report depends on the vigilance of everyone MORE on Thursday, claiming he is “aiding and abetting the enemy” in the "War against Isis" and "Cyberwar against Russia."

“Donald Trump is committing Treason against The United States of America,” Reiner tweeted Thursday. “He is aiding and abetting the enemy in The War against Isis and The Cyberwar against Russia."

"He has turned the world’s oldest Democracy into a wholly owned subsidiary of Vladimir Putin. GOP, WAKE UP!” he added.  

On Friday, Reiner claimed Trump is "mentally unstable" and accused the president of taking steps to "destroy" U.S. independence.

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"Each day this mentally unstable man takes a step closer to destroying 242 yrs. of self rule. And though Democrats want to be restrained, impeachment is inevitable," he tweeted.

"Then GOP Senators will have to make a choice. Either protect Democracy or continue to enable an ignorant criminal," he added. 

Reiner's comments came one day after Trump declared victory against ISIS in Syria and announced his administration's decision to withdraw troops from the nation.

The announcement drew bipartisan criticism, prompting a group of senators from both parties to send a letter to Trump on Wednesday asking him to reconsider his decision.

“If you decide to follow through with your decision to pull our troops out of Syria, any remnants of ISIS in Syria will surely renew and embolden their efforts in the region," they wrote. 

The senators, including  Lindsey GrahamLindsey Olin GrahamHillicon Valley: House Dems subpoena full Mueller report | DOJ pushes back at 'premature' subpoena | Dems reject offer to view report with fewer redactions | Trump camp runs Facebook ads about Mueller report | Uber gets B for self-driving cars DOJ: Dem subpoena for Mueller report is 'premature and unnecessary' Dems reject Barr's offer to view Mueller report with fewer redactions MORE (R-S.C.), Jeanne ShaheenCynthia (Jeanne) Jeanne ShaheenNew Hampshire senator to ask 2020 Dems to back repeal of state residency law Embattled senators fill coffers ahead of 2020 William Barr is right to investigate FBI actions during 2016 campaign MORE (D-N.H.), Joni ErnstJoni Kay Ernst Embattled senators fill coffers ahead of 2020 GOP senators divided on Trump trade pushback Abrams: Schumer has been 'relentless but thoughtful' about Senate bid MORE (R-Iowa), Angus KingAngus Stanley KingAngus King: 'Mueller passed the obstruction question to the Congress and Barr intercepted the pass' Hillicon Valley: Washington preps for Mueller report | Barr to hold Thursday presser | Lawmakers dive into AI ethics | FCC chair moves to block China Mobile | Dem bill targets 'digital divide' | Microsoft denies request for facial recognition tech Dems introduce bill to tackle 'digital divide' MORE (I-Maine), Tom CottonThomas (Tom) Bryant CottonOvernight Defense: Senators show skepticism over Space Force | Navy drops charges against officers in deadly collision | Trump taps next Navy chief Senators show deep skepticism on Space Force proposal GOP senators introduce bill to reduce legal immigration  MORE (R-Ark.) and Marco RubioMarco Antonio RubioSenate Republicans tested on Trump support after Mueller Cuban negotiator says Trump's efforts to destabilize Cuba's government will fail Freedom to Compete Act would benefit many American workers MORE (R-Fla.), expressed concern that the decision would bolster Russian influence in the region. 

"As you are aware, both Iran and Russia have used the Syrian conflict as a stage to magnify their influence in the region," the senators added. "Any sign of weakness perceived by Iran or Russia will only result in their increased presence in the region and a decrease in the trust of our partners and allies."

Reiner has been a frequent critic of Trump, often taking to Twitter to lambast the president.

Reiner has called for Americans to increase their protests against the president, saying in June that he didn't think there was a "line" that could be crossed when it came to demonstrating against Trump.