Lithuanian armed forces consist of some 13000 soldiers and officers.
The Primary mission of the Lithuanian military (in popular opinion) is to defend Lithuania from a possible Russian invasion. While Lithuanian military has a good public confidence (over 50%), many have serious doubts it could ever successfully achieve its goal alone (as Russia has a population 50 times larger than Lithuania).
Therefore joining NATO alliance was a key priority, successfully achieved in 2004. Every NATO country is obliged to defend every other country. As NATO includes superpowers such as the USA, Lithuania could theoretically muster a game-changing help.
After joining NATO, the main Lithuanian military deployments were in far-away lands such as Iraq and Afghanistan, primarily in the US-led operations. Lithuanian Special Forces ("Aitvaras") were instrumental in these, lauded as the crown gem of Lithuanian military and among the best such units of NATO. In a decade of foreign deployments Lithuanian military suffered merely 2 casualties.
Even though Lithuania had no direct interests in these wars, no major anti-war rallies ever took place in Vilnius. There is a rather wide consensus among Lithuanians that helping the Western allies in their wars is needed to ensure that Lithuania would not be "left alone" should it need help defending itself.
The notion popular before 2014 was that Lithuania mainly needs a small-but-modern force to regularly fight in the US-led wars, and, in return, it would be able to swiftly request tremendous NATO firepower should the "Russian peril" arise. As such, the Lithuanian armed forces were severely downsized ~2004 and conscription was abolished in 2008. Military funding went under 1% of GDP, well below the NATO target of 2%. Any political suggestions to redistribute budget typically included "decreasing military expenditures" as a possible source for additional money. The general beliefs were that "1. Lithuanian military will be incapable od standing against Russia alone regardless of funding. 2. Nobody else would attack Lithuania. 3.Small funding is enough if contributing to NATO missions is the sole aim of the military".
After the 2014 Russian aggression in Ukraine, that popular conception changed. Western inaction in helping Ukraine and not even voicing requests for Russia to abandon territories it had "easily" annexed (e.g. Crimea) made Lithuania believe that it should boost up its defensive capabilities in order to at least withstand Russian invasion longer. The new belief is that nobody (including NATO allies) would likely come to liberate Lithuania after it falls under occupation, however, they would be more likely to help Lithuania should it still be fighting for itself.
Conscription was thus swiftly reintroduced in 2015, mainly to boost the soldier numbers and train more men into the depleting reserves. ~3000 people are conscripted for each period of 9 months. Men 19-26 years old could be conscripted involuntary, while women and those between 27 and 38 years old may do the service voluntarily. Some have criticized such "militarization" and suggested Lithuania should avoid Russia by "keeping a low profile" instead, although continuing Russian aggression caused a decline of such opinions among top politicians.
Lithuania has replaced nearly all Soviet weaponry by Western arms. The armed forces also cooperate (e.g. operate joint battalions) with neighboring countries (Latvia, Estonia, Poland, Ukraine) that feel the same dangers.
Lithuanian land army, navy and air force
Lithuanian land forces (~3500) are the key element of the military and the ultimate line of Lithuanian defense. The full-time soldiers are supplemented by Lithuanian volunteer forces of some 4500, who serve part-time, also having civilian jobs. The weaponry is largely defensive. Vehicles are limited to personnel and freight carriers (there are no tanks).
Lithuanian navy is small (11 ships with a crew of 20-40 each, ~600 personnel), mainly doing search-and-rescue, WW2 minesweeping, and patrol duties. With a shoreline of just 99 km and no enemies beyond the seas, Lithuania is not expecting any naval battles.
Lithuanian air force (~1000 personnel) has no fighters or bombers as they are deemed too costly and unnecessary for a small nation. Instead, the Lithuanian airspace is safeguarded from foreign intrusions by NATO forces stationed in Šiauliai. Every 3 months a different NATO country takes up the mission and deploys a group of fighters in Lithuania. However, they are supported by Lithuanian-operated airbase personnel, radars, and anti-aircraft units. Lithuanian air force also owns 8 transport planes, 2 helicopters, and 5 training aircraft.
Several Lithuanian organizations have a dual purpose and would be absorbed by the armed forces in case of war - these are the 1500 anti-riot policemen and 4800 border guards. The Lithuanian Riflemen's Union ("Šauliai"), a civilian paramilitary organization, is also expected to provide troops in wartime. Having lost the prestige it had before its destruction by Soviets, it has been growing in popularity recently.
Military intelligence and counter-intelligence are provided by the clandestinely-named Second Department of Operational Services (there is no first department).