BRUSSELS (Reuters) - The aborted mutiny by the Wagner mercenary group in Russia demonstrates that Moscow committed a strategic mistake by waging war on Ukraine, NATO Secretary-General Jens Stoltenberg said on Monday.

"The events over the weekend are an internal Russian matter, and yet another demonstration of the big strategic mistake that President (Vladimir) Putin made with his illegal annexation of Crimea and the war against Ukraine," he told reporters on a visit to Lithuania's capital Vilnius.

"As Russia continues its assault, it is even more important to continue our support to Ukraine."

(Reporting by Sabine Siebold and Bart Meijer; Editing by Alison Williams)