Some 450 German troops are leading NATO's 1,000-strong multinational battalion in Lithuania.
"Security and territorial integrity is the joint and shared task and responsibility of all those united in (...) NATO," German President Frank-Walter Steinmeier told reporters in Rukla.
"We are here, because we are aware of the fact that the security situation has changed in the last few years. It has become somewhat less predictable and it has become less safe, less secure," he added.
Lithuanian President Dalia Grybauskaitė said that Germany is currently demonstrating leadership in ensuring the security of NATO's eastern flank and the whole of the Alliance.
She said that the multinational battalion in Lithuania provides "both defense and deference at the same time".
NATO this year deployed multinational battalions in the three Baltic countries and Poland as a deterrent to Russia following its actions in Ukraine and the Baltic Sea region. Moscow says that the Alliance's actions threaten its security.