IBTimes UK

A new law allowing Japan's Self-Defence Forces (SDF) to participate in armed conflicts overseas took effect on Tuesday, marking the most decisive break yet from the pacifist principles the country adopted after the end of World War II.

Prime Minister Shinzo Abe, who vigorously pushed through the legislation, has said the law is vital to meet new challenges including a rising China.

Chief Cabinet Secretary Yoshihide Suga said the legislation is "vital to prevent wars and protect the people's lives and livelihoods amid an increasingly severe security environment surrounding our country."

While China strongly criticises the move, ally US has extended support. South Korea, which holds grouse over Japan's war time excesses, concedes that the unfolding security situation in the region justifies a bolstering of defence strategy.

Under Prime Minister Abe, Japan has adopted a decidedly more aggressive defence policy, vigorously shaking off its decades-old 'pacifist' tag.

On 18 September 2015, Japan's parliament approved military operations overseas, marking the end of a 70-year 'pacifist' commitment that "the Japanese people forever renounce war and the threat or use of force."

While Japanese opposition denounced the legislation as 'war bills,' supporters said the bill only allows for a broader interpretation of the pacifist constitution and the Article 9, which stipulated that "land, sea, and air forces, as well as other war potential, will never be maintained."

Here's a look at the slow and steady evolution of Japanese pacifism over the years.

World War II aftermath

Japan emerged from the World War II with deep scars on its conscience and the country undeniably gravitated to an anti-war stance. The post-war Constitution, which was drawn up when the country was under the US occupation, limited the use of force only as a means of self defence. The crux of Japan's pacifist stance was that the country will refrain from using force to resolve international conflicts. This essentially ruled out military alliances and intervention in regional military conflicts.

1950s and Korean Crisis

The tinkering of Japanese pacifism started in the early 1950s when the US nudged Japan to 're-arm' as it looked to bolster its position during the Cold War.

As the Korean War erupted the US withdrew its forces from Japan, leaving the country with no military to protect itself from any possible invasion. Then, under the behest of the US, a 75,000-strong National Police Reserve was formed in Japan to fill the military vacuum.

Again, the regional balance had significantly changed from 1945 with Chiang Kaishek losing the Chinese civil war. The emergence of Mao and the communists in China meant that America lost another regional ally, and this was at the root of US rethinking on Japan's total pacifism.

Prime Minister Yoshida did not give in to pressure to form a military force for self defence and take on bigger stakes in the region but eventually in 1952 a new National Safety Agency was set up to oversee the NPR.

As per the post-war constitution Japan was never to have a regular army, navy or air force and hence the NPR was seen merely as an extension of the police force. However, the National Safety Agency eventually became the Japan Defence Agency or the Ministry o Defence.

In 1954, the National Police Reserve became the Japan Self-Defense Forces but Yoshida made sure the forces were minimalist.

In the 1970s US President Richard Nixon renewed US pressure on Japan to assume bigger regional role.

In 1983, Prime Minister Yasuhiro Nakasone wanted to make an 'unsinkable aircraft carrier' triggering protests. Also under his rule Japan breached for the first time the de-facto military spending limit of less than 1 percent of GDP.

Nakasone also cut a new path, allowing the export of military hardware to the US.

1990-91 Gulf War

Japan spent $13 billion in the war but with no active military participation, setting off debate over the country's efficacy in strategic interventions, this time the oil supplies. The call for becoming a 'normal nation' gained more traction.

Also a prosperous China's rising defence budget in the 1980s spooked Japan.

Japan initiated a plan to build a ballistic missile defence system (BMD) with US cooperation after the 1998 North Korea missile tests. In 2003 Prime Minister Junichiro Koizumi proclaimed BMD a national priority.

In 2001, in a minor yet symbolic departure from the stance during 1990-91 Gulf War, Koizumi decided to support America's war on terror following the 9/11 al-Qaeda attack, by sending forces to the Indian Ocean.

In 2007, marking the 60th anniversary of the Japanese Constitution, Prime Minister Shinzo Abe called for a "bold review" of the charter that paved the way for Japan's greater role in regional and global security.

Under Shinzo Abe again, in 2014 Japan ended a ban on its armed forces abroad. The ban had been in place since 1945. Ending military seclusion by approving collective self defence meant that Tokyo can extend military support to a friendly country under attack, something which it had been proscribed from doing for decades.