"The war in Ukraine matters for all of us, and therefore we're also very grateful for the support that Japan is providing, using also the planes and the cargo capabilities," Stoltenberg said during a brief speech after surveying the Japanese Self Defence Force's Iruma Air Base.
His trip, which included a stop in South Korea, is aimed at bolstering ties with Western allies in Asia in the face of the war in Ukraine and rising competition with China.
Speaking in Seoul on Monday, Stoltenberg urged South Korea to increase its military support to Ukraine, citing other countries that have changed their policy of not providing weapons to countries in conflict following Russia's invasion.
Russia calls the invasion, launched on Feb. 24, a "special operation" to ward off threats to its own security.
(Reporting by Sakura Murakami and John Geddie; Editing by Himani Sarkar and Gerry Doyle)
