MOSCOW -- Russia is solely responsible for the demise of the Cold War-era Intermediate-Range Nuclear Forces (INF) Treaty that officially ended Friday (August 2), various officials say.
At the same time, analysts warn the Kremlin is preparing to deploy new weapons, raising the spectre of another arms race.
"Russia bears sole responsibility for the demise of the treaty," NATO said, accusing Moscow of violating the pact that limited the use of medium-range missiles, both conventional and nuclear.
"We regret that Russia has shown no willingness and taken no demonstrable steps to return to compliance with its international obligations."
The weapon in question is the SSC-8/9M729 cruise missile system, which Washington and NATO say violates the treaty.
The missile has a range of about 1,500km according to NATO, though Moscow says it can travel only 480km.
The INF Treaty prohibited the use of ground-based missiles with ranges of 500 to 5,500km.
"NATO will respond in a measured and responsible way to the significant risks posed by the Russian 9M729 missile to Allied security," the alliance said.
"We have agreed a balanced, co-ordinated and defensive package of measures to ensure NATO's deterrence and defence posture remains credible and effective," it said.
INF Treaty 'dead'
US Secretary of State Mike Pompeo announced Washington's formal withdrawal in a prepared statement, minutes after Russia pronounced the treaty to be "dead".
"Russia failed to return to full and verified compliance through the destruction of its noncompliant missile system," he said in a statement.
"Russia is solely responsible for the treaty's demise," he said.
The United States is "seeking a new era of arms control that moves beyond the bilateral treaties of the past", said Pompeo.
After years of formal complaints and attempts at diplomatic resolution, the United States, backed by evidence supported by all NATO allies, concluded that Russia "openly violates" the INF Treaty.
The Kremlin tried to deflect the mounting criticism of its behavior by suggesting the United States had run a "propaganda campaign" accusing Russia of violating the deal, the Russian Foreign Ministry said in a statement Friday.
Russian President Vladimir Putin suspended participation in the treaty in March.
"A situation whereby the United States fully abides by the Treaty, and Russia does not, is not sustainable," NATO said.
"Russia's been messing around for a long time, first denying this missile exists, then acknowledging it does exist but saying it's in line with the agreement," Russian military analyst Alexander Golts said.
"As early as 2007, when Russia withdrew from the CFE Treaty [on conventional weapons in Europe], the Russian military and the Kremlin said that the INF Treaty was not a good agreement, that it was not fair," Russian military analyst Pavel Felgenhauer told AFP.
Russia developing new weapons
"Now that the treaty is over, we will see the development and deployment of new weapons," Felgenhauer said. "Russia is already ready."
Putin first discussed the new weapons late last year in front of high-ranking officers, and he gave further details in February.
In addition to the creation of a medium-range land-based missile, Moscow plans to develop a land-based version of the Kalibr missiles that have already successfully been used by the navy and tested in Syria.
But Moscow has financial constraints.
It has struggled to emerge from a 2014 economic crisis caused by sanctions and a fall in oil prices. Its military budget is a tenth of the size of Washington's.
The new missiles must be developed "without increasing the Defence Ministry's budget", Putin has specified.
This reluctance to boost spending may be a hangover from the Soviet Union, which collapsed partly under the burden of huge military spending, observers say.
NATO: No new arms race
The demise of the INF Treaty has sparked fears of a new era of weapons development.
The INF deal was seen as one of two key arms treaties between Russia and the United States -- the other being the New Strategic Arms Reduction Treaty (New START), which keeps the nuclear arsenals of both countries well below their Cold War peak.
However, this deal too is set to expire in 2021, and there appears to be little political will to negotiate an extension.
"The chances that this will carry on are low," said Alexander Savelyev of the Russian International Affairs Council think tank. "Nothing then will limit the new nuclear arms race between the United States and Russia."
The allies, though, will avoid "a new arms race", NATO Secretary-General Jens Stoltenberg said.
"We don't want a new arms race, and we have no intention to deploy new land-based nuclear missiles in Europe," he said Friday at a news conference in Brussels.