Russia's continued violations of the Intermediate-Range Nuclear Forces (INF) Treaty are prompting the United States to leave the 31-year-old pact.
US President Donald Trump confirmed his intention to abandon the INF on October 20.
"We're the ones who have stayed in the agreement and we've honoured the agreement," Trump told reporters. "Russia has violated the agreement. They've been violating it for many years."
The treaty, signed in 1987 by then-US President Ronald Reagan and the last Soviet leader, Mikhail Gorbachev, bans the possession, production or testing of ground-launched missiles that can travel distances of between 500-5,500km, as well as their launchers.
Such missiles, mainly designed for a nuclear war in Europe, were difficult to locate and increased instability, according to leaders at the time.
After Gorbachev and Reagan signed the document, the two countries destroyed almost 2,700 missiles.
Russia's 'untenable' violations
Public concern over Russian non-compliance dates back to 2014, when the US State Department said in an annual report that "the Russian Federation is in violation of its obligations under the INF Treaty", and that the United States had raised these concerns with Moscow in 2013.
The same reports for 2015, 2016, 2017, and 2018 repeated the claim.
The United States revealed in early 2017 that a new Russian ground-launched cruise missile known variously as the SSC-8 or the 9M729 breaches the INF Treaty. The weapon has a range of 2,500km, falling within the prohibited range, the Economist reported last year.
Russia has secretly deployed two operational battalions, each with about 36 missiles, with at least one situated in Russia's central military district, putting it in range of targets in Europe, according to the US administration.
Another potential issue is the RS-26 land-based ballistic missile, the legality of which analysts debate.
US Defence Secretary James Mattis October 4 warned that Washington would respond if Russia refused to end its "blatant violation" of the INF, AFP reported.
"Russia must return to compliance with the INF treaty, or the United States will need to respond to its cavalier disregard for the treaty's specific limits," Mattis said after a meeting of NATO defence ministers in Brussels, referring to the SSC-8.
"Make no mistake -- the current situation with Russia in blatant violation of this treaty is untenable," he said.
NATO Secretary General Jens Stoltenberg also said Russia was imperilling the agreement, which he has called a "cornerstone" of European security.
"We believe this treaty is in danger because of Russia's actions. After years of denials, Russia recently acknowledged the existence of a new missile system, called 9M729," he said. "This system is destabilising. It is a serious risk to our security."
Without credible explanations, the most obvious answer is that Russia is indeed breaching the treaty, Stoltenberg said.
"Russia is violating the provisions of the treaty by deploying new missiles," Polish Foreign Minister Jacek Czaputowicz said in Brussels last week, according to Defence24.pl. "If this treaty has ceased to function, because it's already been broken, the question does arise of whether it should still be observed."
Even some Europeans who want the treaty to stay in effect point to Russia's guilt.
"Nobody is questioning Russia's violation of the treaty," an anonymous diplomat told Le Figaro of Paris in an article published October 26. "But abrogation would allow Moscow to blame us for the end of this historic accord."
Denials and threats
Russia denies violating the agreement, but Putin has made no secret of his facetious approach towards nuclear security.
Putin joked on October 18 that in the event of a nuclear exchange, "We, as victims of aggression, as martyrs, will go to heaven. [The aggressors] will simply die because they won't even have time to repent."
Putin, characteristically, has already threatened any countries that might consider hosting US missiles if the treaty ceases to exist.
"The European nations that would agree to [taking the US missiles] should understand that they would expose their territory to the threat of a possible retaliatory strike," he said in Moscow October 24, according to Radio Free Europe/Radio Liberty.
Meanwhile, in an attempt to put blame on the United States for leaving the treaty, Russia on October 25 proposed a draft resolution at the United Nations (UN) that would preserve the INF, according to diplomatic sources.
Fifty-five countries on a UN General Assembly committee specialising in disarmament voted against putting the debate on the agenda, while 31 voted in favour and there were 54 abstentions, AFP reported.