Filmmaker Rob Reiner slammed President TrumpDonald John TrumpCould Donald Trump and Boris Johnson be this generation's Reagan-Thatcher? Merkel backs Democratic congresswomen over Trump How China's currency manipulation cheats America on trade 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 GrahamScarborough sounds alarm on political 'ethnic cleansing' after Trump rally The Hill's Morning Report: Trump walks back from 'send her back' chants GOP rattled by Trump rally MORE (R-S.C.), Jeanne ShaheenCynthia (Jeanne) Jeanne ShaheenPoll: McConnell is most unpopular senator How to reduce Europe's dependence on Russian energy Epstein charges show Congress must act to protect children from abuse MORE (D-N.H.), Joni ErnstJoni Kay ErnstTrump angry more Republicans haven't defended his tweets: report Republicans scramble to contain Trump fallout House Dems, Senate GOP build money edge to protect majorities MORE (R-Iowa), Angus KingAngus Stanley KingPoll: McConnell is most unpopular senator Senate panel advances Pentagon chief, Joint Chiefs chairman nominees Overnight Defense: Highlights from Defense pick's confirmation hearing | Esper spars with Warren over ethics | Sidesteps questions on Mattis vs. Trump | Trump says he won't sell F-35s to Turkey MORE (I-Maine), Tom CottonThomas (Tom) Bryant CottonLawmakers introduce bill to block U.S. companies from doing business with Huawei Five things to know about Iran's breaches of the nuclear deal Hillicon Valley: Trump gets pushback after reversing course on Huawei | China installing surveillance apps on visitors' phones | Internet provider Cloudflare suffers outage | Consumer groups look to stop Facebook cryptocurrency MORE (R-Ark.) and Marco RubioMarco Antonio RubioRepublican lawmakers ask Trump not to delay Pentagon cloud-computing contract Overnight Defense: US shoots down Iranian drone | Pentagon sending 500 more troops to Saudi Arabia | Trump mulls Turkey sanctions | Trump seeks review of Pentagon cloud-computing contract EU official in Canada says he feels 'at home' there because no one was shouting 'send him back' 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.