President Gitanas Nauseda called attention to the deal brokered by Belarus to defuse the crisis, which will see Wagner boss Yevgeny Prigozhin heading into exile in Belarus.
Belarus shares a border with NATO-member Lithuania. Lithuania also borders Russia's Baltic Sea exclave of Kaliningrad.
Nauseda warned that Prigozhin's presence in Belarus and the turmoil in Russia has put the region in a dangerous situation.
"I am talking here not only about Lithuania, but about NATO as a whole," Nauseda said, according to Lithuanian radio.
"We are dealing with a large state, a nuclear state, and any internal unrest inevitably has consequences for the security of surrounding states," Nauseda said, referring to Russia.
He said he had no information so far confirming whether the Wagner chief was already in Belarus, a country which is closely allied with Russia.
He announced that Lithuania would deploy more intelligence resources to assess "political and security aspects" in Belarus.
This Monday, NATO Secretary General Jens Stoltenberg is in Vilnius for a meeting with Nauseda in preparation for the July 11-12 NATO summit in the Lithuanian capital. A key topic at the meeting will be Russia's war against Ukraine.
