Sweden's parliament has voted 291 to 21 to give NATO more access to the neutral Nordic country for training exercises and in the event of a war.
Sweden is outside of NATO, but has moved closer to the alliance recently because of heightened tensions with Russia, cooperating with NATO states like Denmark, Norway, and Iceland and participating in operations in Afghanistan.
"This deal will not change our relationship with NATO nor our security policy. We will remain nonaligned," Defense Minister Peter Hultqvist said. "There will be no NATO troops on Swedish soil without an invitation."
Sweden's closeness to NATO has already angered Moscow. In April, Foreign Minister Sergei Lavrov told the daily Dagens Nyheter that Russia would take unspecified action if Sweden joined NATO.
But Russia's annexation of Crimea and backing of separatists in Ukraine have heightened fears in the Baltic region.
Sweden has accused Russian warplanes of carrying out simulated bombing runs near its border and it has warned of Russian spies in the country.
Sweden's center-left government has said it will not join NATO. However, opposition parties favor membership and polls show many Swedes agree.