"US President Donald Trump is not just a criminal for the whole world, he is Adolf Hitler number two," Sherin told Russian media.
Earlier this day, Trump announced he ordered military strikes on Syria.
"[Trump] is a criminal — but that's not enough. One can call him Adolf Hitler of today, because look — he even chose the time, just like when Hitler attacked the USSR," Sherin told reporters.
"This is the second Belgrade, this is a turning point, the Russian Federation has received an act of aggression because, according to all international norms, this is a violation of all international rights. This is a declaration of war against a sovereign state, towards which a nuclear power is fulfilling its obligations of help and security," Sherin said.
"Everything we've done, all the effort put into this, they try to multiply it all by zero and simply put Russia on its knees," he added.
The strike on Syria is a ill-thought and provocative step by the US that can lead to unpredictable consequences, said his colleague, Yuri Shvytkin a deputy chairman of the State Duma Defense Committee.
"I think this is an ill-thought, half-baked, let's say, provocative, short-sighted step from US authorities' side that can lead to unpredictable consequences," he told reporters.
The actions of France, the UK and the US in Syria do not help to build more constructive relations with Moscow, he added.
Shvytkin said that an emergency session of UN General Assembly is required in order to condemn the actions of the US and its allies.
The US seeks to conduct a strike in Syria in order to disavow the victory of Russia and its partners, said Alexei Chepa, deputy chairman of State Duma Committee on International Relations.
The actions by the US and its allies will not go without consequences. All responsibility lies with Washington, London and Paris, Russian Ambassador to US Anatoly Antonov said, commenting on the strike.
"The worst apprehensions have come true. Our warnings have been left unheard. A pre-designed scenario is being implemented. Again, we are being threatened. We warned that such actions will not be left without consequences," Antonov said on Friday. "All responsibility for them rests with Washington, London and Paris."
The Western nations have conducted a strike on a capital of a sovereign state that strives to survive terrorist aggression, the Russian Foreign Ministry said in a statement.
Foreign ministry spokeswoman Maria Zakharova wrote on Facebook: "those behind all this claim moral leadership in the world and declare they are exceptional. You need to be really exceptional to shell Syria's capital at the moment when it had gained a chance of a peaceful future."