Dmitry Peskov, Russian President Vladimir Putin's spokesman, told journalists that Moscow would follow "with the greatest attention... the rhetoric at the talks and the decisions that will be taken and put on paper".

Arming Ukraine's air defences is expected to top the agenda at the summit marking NATO's 75th anniversary, after missile strikes on Monday hit a children's hospital in Kyiv and killed 38 people.

Peskov said NATO "is an alliance that considers Russia an enemy, an opponent".

NATO "has regularly declared its aim to inflict a strategic defeat on Russia on the battlefield" and "is taking part directly in the Ukrainian conflict on the side of Ukraine", he added.