The Kaliningrad-Moscow train was stopped for a border check at the Kybartai border checkpoint at around 9 p.m. as it crossed into Lithuania from the exclave.
The inspection was carried out by border guards and a serviceman from the Movement Control Center of the Lithuanian Armed Forces.
"The document check revealed that four Russian servicemen were in a compartment, but they wore civilian clothes," Giedrius Misutis, the spokesman, told BNS.
A check of their documents showed that they were Russian servicemen aged 28, 32, 34 and 36 years.
A group of four or more servicemen traveling in transit via Lithuania are considered a military team and they need special permission to continue their journey through the country. The four Russians did not have such permission.
The servicemen were ordered to leave the train and were sent back to Russia on another train before midnight, the spokesman said.
Detentions of Russian military teams in Lithuania were more frequent a decade ago. No such teams were detained either this year or last year.