MANILA, Philippines — Canada and the Philippines, both staunch critics of China’s increasingly coercive actions in the disputed South China Sea, were to sign a key defense agreement on Sunday that would allow their forces to hold joint battle-readiness drills and expand a web of security alliances to deter aggression, Philippine officials said.

Canada and other Western nations have been bolstering their military presence in the Indo-Pacific to help promote the rule of law and expand trade and investment in the region. The moves dovetail with President Ferdinand Marcos Jr.’s efforts to build defense ties with other countries to help his country’s underfunded military face a militarily superior China in the disputed waters.

There was no immediate comment from China, which has accused the P

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