The Lithuanian president announced the government will reintroduce conscription for 5 years, due to the "current geopolitical environment".
President Dalia Grybauskaite said conscription, abolished by parliament in 2008, would aim to "enhance and accelerate army recruitment".
Western officials have warned Russia could expand its controversial actions in eastern Ukraine to Baltic states, including Lithuania, which was a Soviet state and joined Nato in 2004.
Valdis Dombrovskis, vice president of the European Commission, said a stronger NATO presence was needed on the alliance's borders, according to Reuters.
"Russia's aggression against Ukraine is very worrying for Baltic states," Mr Dombrovskis, a former prime minister of Latvia, said at an event in London last week.
"It shows that Russia is looking to redraw Europe's 21st century borders by force, and it must be noted that Ukraine is not the first country to face Russia's aggression."