Filmmaker Rob Reiner slammed President TrumpDonald John TrumpCensus Bureau spends millions on ad campaign to mitigate fears on excluded citizenship question Bloomberg campaign: Primary is two-way race with Sanders Democratic senator meets with Iranian foreign minister 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 GrahamGraham warned Pentagon chief about consequences of Africa policy: report Senate braces for fight over impeachment whistleblower testimony US defense chief says Taliban deal 'looks very promising' but not without risk MORE (R-S.C.), Jeanne ShaheenCynthia (Jeanne) Jeanne ShaheenOvernight Health Care: Appeals court strikes down Medicaid work requirements | Pelosi's staff huddles with aides on surprise billing | Senate Dems pressure Trump to drop ObamaCare lawsuit Senate Democrats pressure Trump to drop ObamaCare lawsuit Trump under pressure to renew last nuke treaty with Russia MORE (D-N.H.), Joni ErnstJoni Kay ErnstErnst endorses bipartisan Grassley-Wyden bill to lower drug prices Progressive group backs Senate candidates in Georgia, Iowa Democrats seek to drive wedge between Trump, GOP on whistleblowers MORE (R-Iowa), Angus KingAngus KingUse of voting tabulation apps raise red flags on Capitol Hill Patrick Dempsey to star in pilot for CBS political drama 'Ways and Means' McConnell, Romney vie for influence over Trump's trial MORE (I-Maine), Tom CottonThomas (Tom) Bryant CottonSunday shows preview: 2020 Democrats jockey for top spot ahead of Nevada caucuses Senate votes to rein in Trump's power to attack Iran Coronavirus poses risks for Trump in 2020 MORE (R-Ark.) and Marco RubioMarco Antonio RubioPeace Corps' sudden decision to leave China stirs blowback Lawmakers raise concerns over Russia's growing influence in Venezuela USDA takes heat as Democrats seek probe into trade aid 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.