Asia-Pacific Defense Commission Act This bill declares that it is U.S policy to continue to maintain a strong military posture in the Asia-Pacific region in order to reassure U.S. allies, deter aggression, and respond swiftly to crises. The Department of Defense (DOD) shall shall seek opportunities to enhance military training and exercises with U.S. allies in such region. The bill authorizes the President to establish the Asia-Pacific Defense Commission to strengthen cooperation between the United States and its allies in such region to combat joint threats. The commission may undertake activities to: strengthen counterterrorism operations and building capacity to track, investigate, and prosecute individuals engaged in terrorist activities; improve regional maritime security and capabilities to interdict illegal arms shipments; bolster regional cybersecurity initiatives and protect critical infrastructure; strengthen military preparedness; facilitate defense-related transfers, subject to the requirements of the Arms Export Control Act; facilitate efforts to enhance training, preparedness, and operations by allies to address North Korean maritime weapons transfers; and coordinate intelligence collected by the intelligence services of the countries participating in the commission, identify the most immediate threats to inform the security services of such countries, and create guidelines for the coordination of multilateral direct action against shared threats. Calls for the U.S. Navy to regularize freedom of navigation operations, in accordance with international law, in the Japanese-administered Senkaku Islands, in the South China Sea, and in regular ports of call at strategic ports in the Asia-Pacific region.