WARSAW, Poland (AP) — NATO’s new secretary general said Monday he is concerned about the “many violations” of the cease-fire in eastern Ukraine and that it is important for Russia to use its influence to make sure the pro-Russia separatists adhere to it.

Jens Stoltenberg spoke in Poland on his first foreign trip since starting the job last week, a visit meant to reassure an ally on the alliance’s eastern flank, concerned for its security due to the conflict in Ukraine.