The treaty was signed by President Ronald Reagan and Soviet leader Mikhail Gorbachev in 1987. It banned missiles with ranges between 500 and 5,500 km.
But earlier this year the US and Nato accused Russia of violating the pact by deploying a new type of cruise missile, which Moscow has denied.
Washington, however, says it has evidence that Russia had deployed a number of 9M729 missiles - known to Nato as
SSC-8. This accusation was then put to Washington's Nato allies, which all backed the US claim.
US President Donald Trump had announced in February that Washington would pull out from the pact if Russia didn't come into compliance, and set the deadline for August 2, reports say.
Russian President Vladimir Putin suspended his country's own obligations to the treaty shortly afterwards.
"An invaluable brake on nuclear war" was being lost, warned UN Secretary General Antonio Guterres, according to the BBC.
"This will likely heighten, not reduce, the threat posed by ballistic missiles," he added, urging all parties to "seek agreement on a new common path for international arms control".
Analysts fear that the collapse of the historic agreement could lead to a new arms race between the US, Russia and China.
The demise of the INF treaty - the only disarmament pact ever to eliminate a whole category of nuclear weapons - represents a significant setback for advocates of arms control.
( With inputs from IANS )