Russia's foreign minister has warned that US President Donald Trump's plan to withdraw from a nuclear weapons treaty with Russia is a dangerous step.
"This would be a very dangerous step that, I'm sure, not only will not be comprehended by the international community but will provoke serious condemnation," deputy foreign minister Sergei Ryabkov told TASS state news agency.
The treaty is "significant for international security and security in the sphere of nuclear arms, for the maintenance of strategic stability," he stressed.
Mr Trump confirmed that the United States plans to leave a landmark nuclear weapons treaty with Russia over claims Moscow has violated the deal.
The three-decade-old Intermediate-Range Nuclear Forces Treaty, known as the INF, was signed in 1987 by former president Ronald Reagan.
Mr Ryabkov said Russia condemned what he called attempts by the US to gain concessions "through a method of blackmail".
If the US continues to act "clumsily and crudely" and unilaterally back out of international agreements "then we will have no choice but to undertake retaliatory measures including involving military technology," Mr Ryabkov told RIA Novosti news agency.
"But we would not want to get to this stage," he added.
"We're the ones who have stayed in the agreement and we've honoured the agreement, but Russia has not unfortunately honoured the agreement, so we're going to terminate the agreement and we're going to pull out," Mr Trump told reporters in Elko, Nevada.
"Russia has violated the agreement. They've been violating it for many years. I don't know why president (Barack) Obama didn't negotiate or pull out. And we're not going to let them violate a nuclear agreement and go out and do weapons (while) we're not allowed to."
Washington's move to pull out of the treaty is motivated by a dream of a single global superpower, Russian state news agencies have cited a foreign ministry source as saying.
"The main motive is a dream of a unipolar world. Will it come true? No," a foreign ministry source told RIA Novosti state news agency.
The official said that Russia has "many times publicly denounced the US policy course towards dismantling the nuclear deal."
Washington "has approached this step over the course of many years by deliberately and step by step destroying the basis for the agreement," the official said, quoted by Russia's three main news agencies.
"This decision is part of the US policy course to withdraw from those international legal agreements that place equal responsibilities on it and its partners and make vulnerable its concept of its own 'exceptionalism'," the official said.
Russian senator Alexei Pushkov wrote on Twitter that the move was "the second powerful blow against the whole system of strategic stability in the world" with the first being Washington's 2001 withdrawal from the Anti- Ballistic Missile treaty.
"And again the initiator of the dissolution of the agreement is the US," he wrote.