Russian President Vladimir Putin said Thursday that Ukraine’s gamble to seize his country’s territory has backfired by boosting his own military’s advance, a boast he paired with teasing support for Vice President Kamala Harris in the upcoming U.S. election.

Speaking at an economic forum in the far-eastern city of Vladivostok Thursday, Putin said it was the “sacred duty” of the Russian army to do everything to “throw the enemy out” of the border region of Kursk and protect its…