OSAKA – Japan’s alliance with the United States is widely viewed as a crucial counterweight to China’s hegemonic ambitions, which pose significant threats to Asian security. But, although the United States and Japan are conducting joint naval exercises in the East China Sea in order to signal to China that it should tone down its actions over the disputed Senkaku Islands, all is not well with the alliance.

Controversy over the deployment by the US Marines of 12 tilt-rotor V-22 Osprey aircraft to the Futenma Air Base on Okinawa has contributed to the alliance’s decay. The hybrid aircraft – which combine a helicopter’s ability to take off and land vertically with the range, loading capacity, fuel efficiency, and speed of a turboprop airplane – are instrumental to deter possible Chinese or North Korean aggression in the area.

Yet the plans have fueled the most persistent anti-American protests on Okinawa in decades, owing to safety concerns. Indeed, the aircraft’s accident-plagued record includes six fatalities since 2007 and two crashes this year. Given that Futenma is located in a densely-populated urban area that includes more than 100 schools, hospitals, and shops, critics contend that the Osprey would endanger the lives of thousands of island residents.

But the level of outrage over the Osprey deployment is not proportionate to the threat – especially given the aircraft’s benefits. This disparity between fact and perception reflects the root cause of the decay in the bilateral alliance: neither country fully appreciates the ongoing need for the alliance, or the political costs that it must bear for the sake of security.