US President Barack Obama's cancellation of a summit with Vladimir Putin represents a new low in US-Russia relations, which have been eroded not just by the row over US leaker Edward Snowden but a litany of other headaches.
Scrapping a summit is a move unprecedented in US-Russia ties since the Cold War and is bound to be taken as a personal slight against Putin by the Kremlin, which is a stickler for protocol and has already said it is "disappointed".
Obama is still travelling to Saint Petersburg for the September 5-6 G20 summit hosted by Russia but will not, as previously planned, go to Moscow beforehand for a bilateral meeting with Putin.
"There is every sign that Washington and Moscow are moving to a serious chill in relations," Lilya Shevtsova, a political analyst at the Carnegie Moscow Centre, told AFP.
"There are too many questions on which Russia and the United States cannot achieve even the slightest rapprochement."
The United States scrapped the summit one week after Russia granted asylum to former National Security Agency contractor Edward Snowden, who Washington wants to put on trial for leaking details of vast US surveillance programmes.
But the Snowden issue is not an isolated row and just the latest addition to an ever growing list of disputes that have clouded US-Russia relations ever since Putin returned to the Kremlin in May 2012 for an historic third term.
"The Snowden issue is just a pretext for cancelling the visit," the Kommersant daily quoted a Kremlin source as saying. "The Americans are moving away from serious negotiations and their refusal will unavoidably have political consequences."
"A frosty period has come for relations," the source added.
--- 'They have nothing to discuss' ---
Within a year, Russia has banned US families from adopting Russian children, forced NGOs financed from abroad to register as "foreign agents" and rushed through legislation outlawing "homosexual propaganda" for minors.
Meanwhile the two sides are at loggerheads over the conflict in Syria, with Moscow refusing to halt its cooperation with President Bashar al-Assad. A joint US-Russia plan for Geneva peace talks has so far come to nothing.
"All these questions have complicated US-Russia relations to such an extent that Putin and Obama have nothing to talk about in a bilateral meeting," said Shevtsova.
The United States is particularly riled to have received no response from Russia to proposals from Obama for new nuclear arms cuts, something he had envisaged as part of his historic legacy.
Obama is already known as no fan of globe-trotting international summitry and the risk now exists that he will lose interest in Russia policy for the remaining years of his second term until 2017.
The United States is currently not even requesting a bilateral meeting with Putin on the sidelines of the G20 summit in Saint Petersburg, according to people familiar with the situation.
The announcement on August 1 that Russia had granted asylum to Snowden after he had spent more than five weeks languishing in transit at Moscow's Sheremetyevo airport was particularly galling for Washington as it had received no advance warning of the news.
FBI chief Robert Mueller had been in talks with the head of Russia's Federal Security Service (FSB) Mikhail Bortnikov over the issue, creating some hope of finding a solution.
While Obama tried to "reset" relations with Putin's Kremlin predecessor Dmitry Medvedev, he never built up a rapport with the Russian strongman -- as shown by their last encounter at the G8 summit in Northern Ireland, where the two men could barely look each other in the eye.
"Obama's cancellation of the visit means the final burial of the 'reset'," said Alexei Pushkov, head of the foreign affairs committee of the Russian lower house of parliament, lamenting that relations were now in a state of "negative pause".
The last such summit cancellation between Moscow and Washington appears to date back to May 1960 when Soviet leader Nikita Khrushchev stormed out of a Paris meeting with US president Dwight D. Eisenhower in a row over a US spy plane shot down by Moscow.
Eisenhower was due to visit Moscow in June 1960 but the visit was cancelled.