"We remain vigilant and stand ready to further help our allies," Stoltenberg told reporters on a visit to Berlin.
"(Belarusian President Alexander) Lukashenko's regime's use of vulnerable people as a means to put pressure on other countries is cynical and inhumane. NATO stands in full solidarity with all affected allies."
The NATO chief also urged Russia to show transparency about its military build-up close to the Ukraine's borders.
"NATO is monitoring the situation closely and we continue to provide political and practical support to Ukraine," he added.