North Korean leader Kim Jong-un’s latest message of reassurance to Russian President Vladimir Putin, coming shortly after Chinese President Xi Jinping’s visit to Pyongyang, constitutes a form of strategic hedging, according to observers. The letter suggested that Pyongyang-Moscow ties were evolving beyond a largely transactional relationship into a firm military alliance, even as North Korea sought to rekindle its traditional “blood alliance” with China, they said. In a congratulatory message...