Moscow claims its troops were deployed in Belarus for drills that will take place in February. Meanwhile, the West fears the possible invasion of Ukraine by Russia.
"In the current situation, we view the arrival of Russian armed forces in Belarus not only as a destabilizing factor in the security situation but also as the one posing an even bigger direct threat to Lithuania," Anuauskas posted on Facebook.
Moscow says S-400 missile systems will be deployed in Belarus during the military exercise aimed at "preventing external aggression".
Russia has not disclosed how many of its troops will take part in the drills earlier this week announced by authoritarian Belarusian leader Alexander Lukashenko. Minsk says the military exercise will be held amid growing military threats from neighboring Ukraine and Poland.
Anusauskas also said he's set to meet on Wednesday with the ambassadors of nine NATO countries "that actively contribute to boosting Lithuania's security".
"We will discuss the security situation and I will brief them on Lithuania's actions," the minister said.
In response to the tensions in the region, Lithuania has decided to increase the number of army conscripts next year, as well as the number of Ukrainian army instructors, and plans to bring forward the acquisition of rocket systems.