After 1945, one of America’s strategic conundrums in East Asia was Japanese weakness, not strength, in the face of an expansive Soviet Union. Fast-forwarding to today, this conundrum exists in a different form. Xi Jinping’s China is not a revolutionary ideological superpower. But China’s explosive rise, and the danger that it could deploy its military power to pursue territorial aggrandizement in maritime Asia, risks eroding Japan’s security within a regional order that has been remarkably peaceful and prosperous.

The U.S. needs capable allies that can work closely with American military forces to maintain regional peace and deter conflict. Japan needs to secure itself against new dangers — including from North Korean ballistic missiles and nuclear warheads — that did not exist when its national security laws were originally enacted. That is why Washington has such a compelling interest in Prime Minister Shinzo Abe’s campaign to move revised security legislation through the Diet, enabling Japan to better defend itself and cooperate with the U.S. to ensure peace in Asia.

Whereas the Pacific War of 1937 to 1945 was caused partly by an imbalance of power tilted too heavily toward Imperial Japan, in subsequent decades Japan’s disarmament and pacifism risked creating the opposite problem — a vacuum in East Asia that a hostile Soviet Union would have been only too happy to fill. The U.S.-Japan alliance of 1952, and the stationing of forward-deployed American forces there, was designed to compensate for Japanese weakness, giving it the defensive shield the country otherwise lacked, and helping to ignite the Asian economic miracle that has transformed the region.

During the Cold War, American leaders repeatedly pushed Japan to enhance its military capabilities so as to make it a more capable and resilient ally. Instead, Japan devoted its national resources to becoming the world’s second-largest economy, an industrial dynamo the likes of which Asia had never seen. This mission was so successful that, in the late 1980s, it looked as if an island nation only one-third as populous as the U.S. would soon eclipse it to become the world’s No. 1 economy.

China is now Asia’s economic superstar. But its sheer scale and apparent determination to use its newfound power to revise Asia’s territorial order mean that Japan’s policy of pacifism under the American military umbrella is no longer sufficient to protect either Japanese or American interests.

Old rules, new threats

Indeed, under the constitution drafted by Americans during their postwar Occupation nearly 70 years ago and which still governs Japan in 2015, the country forfeits the right to use military force for anything beyond the strictest interpretation of self-defense. The current law actually prevents Japan from defending American forces that are themselves engaged in shielding Japan from an armed attack.

Abe correctly wants to revise a postwar regime that may have been appropriate in 1947, but which actively undermines Japan’s security today in light of new threats. Existing strictures on Japan’s deployment of offensive weaponry would remain in place; tight civilian control over the Japanese military would continue; Japan would move no closer to becoming a militarized power bristling with nuclear ballistic missiles and other weapons of power projection like its neighbors in China and North Korea.

Leaders in Beijing and Seoul — countries once occupied by Japan’s Imperial Army — have mobilized domestic political support by exaggerating Abe’s modest defense reforms as evidence of a new Japanese “militarism.” In fact, Abe’s move to liberalize postwar constraints on Japan’s ability to defend itself and its allies would be welcomed in most Asian capitals.

Nations as diverse as the Philippines, Vietnam, Singapore and India understand that China risks dominating Asia in the absence of countervailing powers. These include Japan and also the U.S., whose regional leadership and military presence are made possible primarily by its alliance with Japan.

The distinguishing feature of the national security legislation before the Diet is not that it would somehow “unleash” Japan’s military power. Instead, it would enable Japan to cooperate with American and other military forces in ways that reinforce Japan’s own security and shore up a regional order that is under stress from North Korean militarism and Chinese revisionism.

Double impact

Japan’s pending defense reforms therefore have a double impact: They would make Japan’s Self-Defense Forces more capable, while enabling them to be better partners to the American forces that still protect Japan and the sea lanes that carry the fruits of Asia’s prosperity. The reforms would also facilitate Japan’s cooperation with friendly countries in Southeast and South Asia that want to protect the region’s peaceful status quo.

Asia’s strategic future hangs in the balance as the region’s powerhouses jostle for influence. For those who see a power equilibrium as a source of stability, a Japan that is better able to defend itself and partner with other Indo-Pacific nations shores up a regional balance that otherwise is in danger of tilting toward China.

For those who believe a continued U.S. military presence is necessary to help reassure insecure Asian states, Japan’s security reforms would put its U.S. alliance on a sounder footing, stabilizing the wider region by facilitating Washington’s future military cooperation with Tokyo.

Similarly, for those who hope Asia can develop robust regional institutions to moderate great-power competition and enable deeper multilateralism, Japan’s new security legislation will enhance Tokyo’s collaboration with South and Southeast Asian partners, strengthening webs of regional cooperation.

Ultimately, Japan’s security reforms are but a small piece of a larger story — the need for the country to adapt its postwar institutions and policies for a new era of competition. By virtue of its U.S. alliance and its development assistance, Japan for many decades has been a vital contributor to regional peace and prosperity. To sustain this role, it needs a more active strategy of shaping its regional environment. Doing so requires additional reforms at home to make Japan what Abe calls a “proactive contributor to peace.”

Ironically, the policies of inertia, disarmament and isolationism that are recommended by some Japanese critics would be more likely to lead to conflict in Asia, by creating a power vacuum and emboldening Japan’s adversaries. A more capable, activist Japan that cooperates closely with the U.S. and other partners will more effectively preserve peace in Asia than one that entrusts the task to revisionist powers, which may not have Japan’s — or the region’s — best interests at heart.

Daniel Twining is senior fellow for Asia at the German Marshall Fund of the United States. He previously served on then-Secretary of State Condoleezza Rice’s policy planning staff and as foreign policy adviser to U.S. Sen. John McCain.