The new US-Japan defense guidelines were agreed upon in New York City on Monday during the 2+2 talks between Japan and the US, where US Defense Secretary Ash Carter and Secretary of State John Kerry are meeting with Japanese Defense Minister Gen Nakatani and Foreign Minister Fumio Kishida.

The senior defense official, who spoke to reporters ahead of the signing, called the agreement a "very big event" that redefines how Japan operates as a military partner around the globe.

Japan will be able to defend regional allies that come under attack , a change that means Japanese missile defense systems could be used to intercept any weapons launched toward the United States — notable, given its close proximity to North Korea, which the official later described as a "growing threat" to regional stability.

In addition, expect to see increased Japanese presence around the globe on peacekeeping and humanitarian missions, and potentially also on intelligence, surveillance and reconnaissance operations.

The guidelines will also lead to the establishment of a standing "alliance coordination mechanism," made up of Japanese and US officials from the defense and foreign relations sides. That body will provide a streamlined way of organizing and controlling US-Japan operations, something that has hindered the military relationship in the past.

Representatives still need to sort out many details, and once the guidelines are finalized, they need to be voted upon in Japan. However, few roadblocks are expected and all signs are the guidance will move forward.

In essence, the guidelines codify the major changes to Japan's military structure laid out last summer by the government of Shinzo Abe. It points toward a Japan that sees itself as increasingly concerned about its ability to meet its security challenges in East Asia, particularly on how to cope with the surging military power and diplomatic confidence of China.

In this, the US and Japan are in broad agreement about how to contain a rising China, lending new regional and strategic heft to the update.

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Narushige Michishita, professor at the National Graduate Institute for Policy Studies in Tokyo, said the new guidelines are fundamental to re-cementing Japan's security guarantee, which is founded on the commitment by the US to aid Japan if attacked.

Through 2014, Japanese officials, echoing domestic sentiment, expressed concerns and reluctance about entanglement — the prospect of getting embroiled in conflicts in which Japan had no direct stake, while negotiating the update to tie the US closer to Japan's need to use the senior partner to deter Japan.

Japan's point of view, Michishita said, does not involve the country flexing its muscles regionally, let alone globally. Japan's upcoming legislation to permit the use of collective self-defense is hedged with caveats and limitations. Similarly, Japan doesn't see the update as a carte blanche for Japan to even defend US ships.

"We regard ourselves as a declining power. The idea, is for example, [is] the ability and know-how [for the] Maritime Self-Defense Force [to defend] a US ship deployed in a Japanese flotilla; it may be possible to defend a US ship when an attack on that ship does not directly or will not directly threaten Japan's security. But technically even that is not allowed," Michishita said.

Soldiers from the US Army train with representatives from Japan's Ground Self-Defense Force during Operation Orient Shield in October

Photo Credit: US Defense Department

Which doesn't mean China or North Korea will be particularly happy with the arrangement. Both nations will likely see this as adding to the power projection capabilities of the US in the region, despite insistence from the official that the new guidelines were not written to target any specific country.

The official said Chinese officials have been briefed on the general guidelines, with the US planning a more detailed brief early this week. He declined to describe the Chinese reactions to the new guidelines.

Jun Okumura, a visiting scholar at the Meiji Institute for Global Affairs in Tokyo, noted that China's posture has been less aggressive toward Japan in recent months.

"The economy can't be the only reason that China is walking and talking more softly around Japan of late," Okumura said. He added that the new guidelines reinforce the "meat and potatoes" of the alliance, including shared intelligence, reconnaissance and weapons systems.

He also warned against expecting Japan to suddenly rise up as a military, expansionist power.

"Too much attention is being paid to headline generators like reinterpreting Article 9 of the Japanese Constitution to accommodate collective self-defense or providing logistic support for UN-sponsored and other international efforts toward securing and maintaining peace," he said. "We will wait a long time before a [Japanese] destroyer is conveniently nearby when the Chinese [Navy] attacks the US 7th Fleet."

Instead, Okumura expects a focus on the "mundane joint efforts in intelligence," such as satellite networks, joint patrols in the South China Sea, and weapons research and development.

The senior US official highlighted space and cyber as two areas where Japan could expand its cooperation with the US under the new guidelines.

Japan has been steadily increasing its presence in space, culminating in a new 10-year space strategy revealed at the start of this year.

In particular, the official noted that the sharing of space situational awareness data could increase under the new guidelines. As space becomes more congested, the US has prioritized its ability to track what is circling the Earth — as well as the ability to split that data with other allied nations.

"Both Japan and the United States have strong capabilities in this area, and we would like to expand our sharing of information in that area," the senior official said.

Whether that means just a greater flow of information between the countries, or if it results in Japan joining the US, UK, Canada, and Australia in the US Air Force's Joint Space Operations Center , is not clear.

Industrial Growth

US industry will likely benefit from the changed relationship in a number of ways, the official said.

"There is provision in the guidelines for increased US-Japan cooperation in the areas of co-development, co-production, [and] defense technology sharing, and we are eager to explore those areas," the official said.

The official also pointed out that under the Defense Innovation Initiative, part of the Pentagon's acquisition reform efforts, there is a push for more industrial cooperation with foreign allies.

"I expect to be discussing that with the Japanese, in particular," the official said.

The military industrial ties between the US and Japan are already strong, particularly given the latter's decision to purchase the F-35 joint strike fighter.

But an expansion of Japan's global presence could coincide with a need to grow its arsenal, particularly if it begins to take part in ISR operations around the globe. The island nation has already agreed to purchase the Global Hawk unmanned system; it could look to increase that buy, or add low-altitude ISR assets such as the MQ-1 Predator or MQ-9 Reaper drones.

Given the emphasis from the senior defense official on missile defense, additional anti-missile systems could also be in play, whether ship- or land-based.