Seventy years ago they crushed Nazi Germany together but raging tensions over Ukraine mean Russia's former World War II allies in the West will snub the Kremlin's showcase victory anniversary celebrations.
As top Western leaders give President Vladimir Putin's Red Square parade on May 9 the cold shoulder, the guest list of those likely to be coming -- including China's president and North Korea's reclusive leader -- shows how Moscow's international standing has shifted.
The leaders of Britain and France will not attend the events marking the 70th anniversary of the Soviet Union's victory over Nazi Germany, and few expect US President Barack Obama to attend the May 9 celebrations either.
German Chancellor Angela Merkel will also skip the main Red Square memorial events, and Poland will hold its own commemorations.
As Russia's confrontation with Washington and Brussels hits post-Cold War lows, the Moscow festivities have come to be seen as a political litmus test, observers said.
"Attending the May 9 festivities in Moscow would be the legitimisation of Putin and the Kremlin through World War II," said political analyst Lilia Shevtsova.
The Soviet Union lost an estimated 27 million during World War II although some say that figure could be higher and victory in the conflict, which in Russia is called the Great Patriotic War, remains an enormous point of pride in the country.
International support at the WWII festivities would be a huge boost for Putin who received an icy reception from Western leaders at the G-20 summit in Australia in November.
In January, he also conspicuously stayed away from ceremonies in Poland marking the 70th anniversary of the liberation of the Auschwitz death camp by the Soviet army.
Presiding over preparations for the Russia-wide festivities this week, Putin said attempts to belittle Russia's role in WWII were aimed at stripping it of its "moral authority."
Germany’s Chancellor Angela Merkel (R) will not be attending the May 9 Red Square parade but she will visit the Russian capital a day later.
"Occasionally we hear sheer lunacy -- it's amazing how people even come to that."
Poland angered Moscow when its foreign minister said it was Ukrainian soldiers -- rather than the Soviet Red Army -- who liberated Auschwitz in 1945.
The Kremlin shrugged off the expected no-shows, insisting that most countries understand the huge symbolism of the commemorations.
Of the 68 invited heads of state as well as chiefs of the United Nations, the Council of Europe, UNESCO and the EU, 26 leaders have already confirmed their participation.
Among those expected in Moscow are Greek Prime Minister Alexis Tsipras, Czech President Milos Zeman and North Korea's Kim Jong-Un, who will make his first foreign trip since coming to power in 2011.
Leaders of India, South Africa, Mongolia, Cuba and Vietnam and a number of ex-Soviet states are also set to attend.
In a compromise gesture, Merkel will visit Moscow on May 10.
Russia has traditionally celebrated Victory Day with much pomp and flair but this year's festivities will be taken to a new level.
More than 2.5 million veterans will be awarded medals, and marches will be held across the country and some ex-Soviet states.
Crowning the commemorations will be a Red Square parade featuring both troops in WWII-era uniforms and Russia's newest weapons.
Troops from more than 10 countries will take part in the parade.
'Hoping to punish Russia'
Taking their cue from the Kremlin, Russian analysts said that by snubbing the Moscow parade Western leaders were showing disrespect to the entire country.
"They are hoping to punish Russia and negate the deaths of 27 million Soviet citizens during WWII," said Vladimir Yevseyev, director of the Public Political Studies Center.
"That Obama won't come is Mr Obama's personal business," he said. "The world cannot depend on what Washington says."
But even some of those who do not shy away from criticising the Kremlin have apparently found the slight unsavoury.
Prominent TV personality Vladimir Pozner wondered what was the stance of France, Britain and the United States on this week's march by Latvian veterans who fought on Nazi Germany's side.
"So would at least one leader make a statement on the subject? And condemn those who march as well as those who applaud them and encourage their actions?"
But others said the Western leaders' expected absence was understandable, referring to Moscow's support for Ukrainian separatists.
"They cannot participate in events with militaristic overtones and marching Russian soldiers," Alexander Baunov, a senior associate at the Carnegie Moscow Center, told AFP.
"What has the memory of the war got to do with this?" added political observer Anton Orekh.
"Why should we equate the feat of the Soviet people and millions of lives paid for the Victory with those who now occupy the Kremlin?"