MOSCOW, May 3 (Reuters) - Dmitry Medvedev, deputy chairman of Russia's Security Council, said on Saturday that President Donald Trump's assertion that the U.S. had done more than any other country to win World War Two was "pretentious nonsense".

Trump posted on social network Truth Social late on Thursday that "nobody was close to us in terms of strength, bravery, or military brilliance" in both world wars, and that "we did more than any other country, by far, in producing a victorious result in World War II."

Medvedev, a former Russian president who has emerged as one of Moscow's most outspoken anti-Western hawks since the start of Russia's war in Ukraine, made his own statement at a time when Washington and Moscow are trying to reset their troubled ties while discussing a possible way to end the conflict.

"Trump recently announced that the U.S. made the biggest contribution to victory in World War Two and that he will introduce a special holiday on May 8. A holiday is not a bad thing, but his first statement is pretentious nonsense," Medvedev said in a post on the VK social network.

"Our people sacrificed 27 million lives of their sons and daughters in the name of destroying accursed fascism (nazism) Therefore, Victory Day is ours and it is May 9! So it was, so it is, so it will always be!" wrote Medvedev. Reporting by Reuters Editing by Andrew Osborn