NATO's new secretary general, Jens Stoltenberg, is in Poland on his first foreign trip since starting the job last week, a visit meant to reassure a nervous ally on the alliance's eastern flank.

Speaking in Warsaw alongside the Polish President, Stoltenberg on Monday stressed that NATO would protect and defend each of its allies.

Since the Russia-Ukraine conflict began this year Polish leaders have repeatedly called for NATO to do more to protect it.

Later in the day, Stoltenberg has meetings with the prime minister and other leaders, and also plans to visit an air base where NATO troops are engaged in training and exercises.