President Donald Trump has signed into a law a bill which imposes new sanctions on Russia for their alleged meddling in the 2016 election.
The bill, which was signed in private at the White House, also imposes sanctions on Iran and North Korea.
Mr Trump accused Congress of overreach on the legislation, which “handcuffs” him from easing Russia penalties.
Moscow denies interfering in the US election, and Mr Trump has denied colluding with the Kremlin.
Hours after the US president signed the bill, Kremlin spokesman Dmitry Peskov said: “This isn’t news.
“The thing is, the bill was approved and was going to automatically become law with or without the president’s signature.”
Moscow had already retaliated by ordering 755 people expelled from its US embassy and consulates.
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Several European nations, including Germany, are also unhappy because the new law could penalise their companies working on pipelines from Russia, for example, by limiting their access to US banks.
European Commission President Jean-Claude Juncker warned of “unintended unilateral effects that impact the EU’s energy security interests”.
In signing the Countering America’s Adversaries Through Sanctions Act, Mr Trump attached a statement calling the measure “deeply flawed”.
He accused Congress, which last week overwhelmingly passed the bill and sent it to the White House, of overstepping its constitutional authority.
“As president, I can make far better deals with foreign countries than Congress,” he said.
The sanctions, which are also in response to Russia’s annexation of Crimea, come months after President Barack Obama expelled 35 Russian diplomats.
Republican Lindsey Graham praised the bill after it passed, pointing out that Mr Trump’s options were limited since there were enough votes to overcome a presidential veto.
“President Putin did something that nobody in America could do. He united the Congress,” the South Carolina senator told CNN.
Senior Russian parliamentarian Konstantin Kosachev said that Mr Trump was “capitulating” by not standing up to Congress.
Mr Trump and Mr Putin met for the first time at the highly-scrutinised G20 summit last month in Germany.
Allegations by the US intelligence community that Russia interfered in the US election to aid Mr Trump are currently being investigated by Congress and a special investigator.
