The NASAMS medium-range air defence systems, which would be the first such shield in the Baltic states, would cost around €100 million ($115 million), defence ministry spokesman Vaidotas Linkus told AFP.
Tensions between the 28-member Nato defence alliance and Russia are running high following Moscow's 2014 annexation of the Crimean peninsula from Ukraine.
Last week, Nato jets were scrambled seven times from its Baltic bases to escort Russian military aircraft over the Baltic sea, according to Lithuania's defence ministry.
Nato agreed in July to deploy four battalions of around 1,000 troops each in the three Baltic states -- Estonia, Latvia and Lithuania -- and Poland to assuage their fears of Moscow.
Long seen as Nato's Achilles heel, Baltic forces alone would be incapable of resisting a full-scale attack brought on by Russian forces and bolstered by Moscow's overwhelming air superiority.
But experts say that their ability to fend off Moscow until Nato could scramble a broader response is decisive. New air defence capabilities would also make any attack more costly.
"The lack of air defence systems increases the likelihood of a successful snap attack with limited forces. Our military power is important for deterrence," retired colonel Ignas Stankovicius told AFP.
Moscow denies any territorial ambitions and accuses the US-led alliance of destroying Europe's military balance around Russian borders.