NATO's chief has expressed serious concerns that China and Russia are increasing military alignment, stressing the importance of working closely together with Japan and other democratic partners.

NATO Secretary General Jens Stoltenberg spoke to NHK on Tuesday during his visit to New York for the United Nations General Assembly.

Referring to the war in Ukraine, Stoltenberg said "China is enabling, propping up the Russian war economy."

He added that the missiles and bombs that Russia uses against Ukraine are "actually produced with technology and components provided by China."

Stoltenberg also said that "What happens in Asia matters for Europe, and what happens in Europe matters for Asia."

He stressed that he has worked hard to further strengthen the "excellent" partnership with Japan and other partners in the Asia Pacific region.

The NATO chief also referred to the US presidential election in November. Some observers say former US President and Republican nominee Donald Trump may decrease his country's involvement with the alliance if he wins back the White House.

Stoltenberg said there is "strong bipartisan support to NATO in the United States," and he believes the country will remain a committed NATO ally, regardless of the outcome of the election.