Latvian Defence Minister Artis Pabriks on Tuesday said the Baltic state would reinstate compulsory military service after growing tension with neighbouring Russia during its war in Ukraine.
"The current military system of Latvia has reached its limit. Meanwhile we have no reason to think that Russia will change its behaviour," Mr Pabriks said.
Latvia had scrapped mandatory service a few years after joining the Nato defence alliance.
Since 2007, the EU member's military has consisted of career soldiers and National Guard volunteers, who serve in the infantry part-time on weekends.
The country of fewer than two million people, which borders Belarus and Russia, only has 7,500 active duty soldiers and National Guard members, backed by 1,500 Nato troops.
Mr Pabriks said the mandatory military service would apply to men and come into effect next year, with several options available for fulfilling the requirement.
Gatis Priede, a National Guard soldier, called the move "the best news" and said the decision should have been made after Russia annexed Crimea in 2014.
"This is the right thing, to train more reservists for our army and for overall Nato strength, which is still critically lacking in the Northern European and Baltic region," Mr Priede told AFP.
Mr Pabriks also announced plans to build another military base near the south-eastern city of Jekabpils, closer to the Russian border than the existing Adazi base.