Moscow, Russia (CNN) -- Millions of Russians have been poring over once secret documents relating to the 1940 execution of nearly 22,000 Polish officers by the Soviet secret police.
The documents, which include an order signed by former Communist dictator Josef Stalin, were posted on the Web site of Russia's State Archive in Moscow's latest gesture of solidarity with Warsaw since Polish President Lech Kaczynski, his wife and 94 officials were killed April 10 in a plane crash on their way to a ceremony to commemorate the massacre at Katyn in western Russia.
Decades of Kremlin denials that Soviet agents were responsible for killings, as well as the widely held view in Russia that Nazi forces had in fact carried out the massacre, have embittered ties between the two nations.
The Kremlin ordered the publication of the files, which were declassified in 1992.
"I recently issued instructions to continue this work so that our own Russian people know better about what happened there, and to publish the results that have already been reached," Russian President Dmitry Medvedev said during a news conference shortly after the release.
"Let everyone see what happened at that time, who made decisions, and who ordered the execution of Polish officers. All written documents are there, with all the signatures," he said.
The centerpiece of the files is a note addressed to Josef Stalin from the notorious Soviet secret police chief Lavrenty Beria, dated March 5, 1940. It recommends the summary execution of the thousands of prisoners of war, including: "Polish army officers, former officials of the Polish police and intelligence services, members of Polish nationalist counter-revolutionary parties, members of unmasked rebel counter-revolutionary organizations, defectors and others.
"They are all sworn enemies of Soviet power, filled with hatred towards the Soviet system," Beria wrote.
The first page of the letter bears the word "Za" -- "in favor" - scrawled in blue pencil with the signatures of Stalin and three Politburo members.
In the first 24 hours after publication on the internet, the Russian-language archive sites received more than 2.5 million hits, crashing the server multiple times as the public clamored to examine the files.
The massacre is an enduring symbol for Poles of their suffering at the hands of the Soviet Union. Moscow acknowledged responsibility in 1990.
The information in the files is already known by historians, but their publication is being seen as an important symbolic step: an effort by the Kremlin to finally dispel widely held myths about the killings in Russia, to confront its past and to set the record straight.
It's also a further sign that long-running tensions between Russia and Poland are finally easing.
Medvedev was one of the few national leaders to brave the ash cloud in European airspace April 18 to attend the funeral of the Polish leader. He told Poles he hoped the tragedy could bring the two nations closer.
CNN's Max Tkachenko contributed to this report.