I have hard time believing that Russia was ever going to “attack” Japan like this Newsweek report is claiming. An attack on Japan would trigger the US-Japan alliance which would lead to an overwhelming military response that would crush whatever attack Russia launched. With that all said, after what we have seen of the Russian performance in Ukraine, the Japanese military could probably defeat any Russian attack without American assistance:

Russia was preparing to attack Japan in the summer of 2021, months before President Vladimir Putin launched a full-scale invasion of Ukraine, an email featuring a letter from a whistleblower at Russia’s Federal Security Service (FSB), shared with Newsweek, reveals.
The email, dated March 17, was sent by the agent, dubbed the Wind of Change, to Vladimir Osechkin, a Russian human-rights activist who runs the anti-corruption website Gulagu.net, and is now exiled in France.
The FSB agent writes regular dispatches to Osechkin, revealing the anger and discontent inside the service over the war that began when Putin invaded neighboring Ukraine on February 24.
Newsweek
You can read more at the link, but what I can believe is that Russia may have been determining the likelihood of succeeding with a provocation against Japan such as sinking one of its naval ships. This would put Japan in tough spot because their constitution would not allow them to undertake offensive operations and thus the Japanese government would turn to the U.S. for support.
This would also put the U.S. in a tough spot because the Biden administration would have to determine if taking offensive action against Russia is worth it in response to a sunken Japanese ship. Putin would likely bet no offensive military action would be taken and instead toothless sanctions and sternly worded letters would be issued. The lack of a response from the U.S. would have put a strain on the U.S.-Japan alliance which is what their ultimate goal may have been. Additionally sinking a Japanese ship would be a morale boost for the Russian Pacific Fleet. I wonder if Putin wishes he would have initiated a provocation against Japan instead of his current disastrous war in Ukraine?









