A landmark arms control treaty that president Ronald Reagan and Soviet leader Mikhail Gorbachev signed three decades ago is dead, prompting fears of a new global arms race.
The US and Russia both formally withdrew from the Intermediate-Range Nuclear Forces (INF) treaty on Friday.
Last year, President Donald Trump announced his decision to pull out from the INF, which has been described as a cornerstone of global security, accusing Russia of violating it by developing a new short-range missile, which Moscow denies.
Under the treaty, neither side was allowed any surface-launched missile that had a range of between 500 and 5,500 km (310–3,420 miles).
If the US and Russia choose not to extend or replace the larger New Strategic Arms Reduction Treaty (START) when it expires in early 2021, there will be no legally binding limits on the world's two largest nuclear arsenals for the first time in nearly a half-century.
The Trump administration says it can now counter Russia - and China - without the constraints of the treaty.
The US has complained for years of an unfair playing field - that Russia was developing weapons that violated the treaty and China, which was not a signatory, was developing similar weapons.
Watch: on 8 December 1987, US President Ronald Reagan and Soviet leader Mikhail Gorbachev signed the INF Treaty in Washington D.C.
The Russian foreign ministry says the US has made a "serious mistake" in formally withdrawing from the INF treaty.
A statement posted on the ministry's website accused the US of spreading "disinformation" about alleged Russian violations in order to "free itself" from the treaty's restrictions.
"Renouncing the INF Treaty confirms that the US is set on a course towards destroying all international agreements that do not suit it for one reason or another," the ministry said.
The statement urged the US to refrain from deploying any new missiles of the kind mentioned in the treaty, and expressed a readiness to maintain dialogue on "restoring trust and strengthening international security".
A NATO spokesperson has said that "Russia bears sole responsibility for the demise of the Treaty": "We regret that Russia has shown no willingness and taken no demonstrable steps to return to compliance with its international obligations.
"A situation whereby the United States fully abides by the Treaty, and Russia does not, is not sustainable.
"NATO will respond in a measured and responsible way to the significant risks posed by the Russian 9M729 missile to Allied security.
"We have agreed a balanced, coordinated and defensive package of measures to ensure NATO's deterrence and defence posture remains credible and effective."
President Donald Trump has not committed to extending or replacing New START, which imposed limits starting in 2018 on the number of US and Russian long-range nuclear warheads and launchers.
Mr Trump has called New START "just another bad deal" made by the Obama administration, and his national security adviser John Bolton said in June that it was unlikely the administration would agree to extend the treaty for five years, which could be done without legislative action in either capital.
The Trump administration thinks talks about extending New START are premature.
The administration claims that with China's growing arsenal of nuclear warheads, Beijing can no longer be excluded from nuclear arms control agreements.
Mr Trump has expressed a desire to negotiate a trilateral arms control deal signed by the US, Russia and China.
"We'll see what happens," he told reporters at the White House on Thursday.
"I will say Russia would like to do something on a nuclear treaty and that's OK with me. They'd like to do something and so would I."