A senior Russian official says the Kremlin has nothing to convey to the international conference that has been discussing a peace plan proposed by Ukraine.
The Tass news agency reported on Saturday that Kremlin spokesperson Dmitry Peskov also said Russia wants "a more focused and promising event."
Japanese Prime Minister Kishida Fumio and US Vice President Kamala Harris took part in the two-day forum that opened on Saturday in Switzerland.
US President Joe Biden signed a massive aid package in April that allowed Washington to resume military support for Kyiv.
The Associated Press on Saturday quoted Ukraine's first deputy minister of defense, Ivan Havryliuk, as saying, "It takes time to load ships that must then cross the Atlantic."
He went on to say: "But we're already seeing the results. Russia's artillery advantage was 7-to-1 at the start of the year, but is down to 5-to-1 now."
President Vladimir Putin said on Friday that Russia has deployed almost 700,000 military personnel to the frontlines of the war in Ukraine.