An extension of Japan’s military reach beyond the East China Sea, where it is embroiled in a territorial dispute with Beijing, to an area where it has no territorial claims would reflect growing disquiet about Chinese naval power.
But it would also add to concerns that under its hawkish leader Shinzo Abe, Japan is determined to raise its military profile on the regional stage to what many believe are unnecessary levels.
The likelihood that Japanese self-defense forces could be involved in checking Chinese ambitions in the South China Sea increased after Japan claimed that the area’s security was inextricably linked to its own.
"We currently do not patrol there or have a plan to do so, but we are deepening our cooperation with the US and the situation in the South China Sea has an impact on our national security, and we are aware that we will need to consider our response," said Japan‘s defense minister, Gen Nakatani.
Mr. Nakatani was speaking soon after Adm. Robert Thomas, commander of the American Seventh Fleet, said that Japanese surveillance ships could supplement efforts to monitor Chinese activity around the Spratly and other islands that are at the center of hotly contested claims by China and several Southeast Asian nations.
"I think allies, partners and friends in the region will look to the Japanese more and more as a stabilizing function," Adm. Thomas told Reuters in a recent interview. "In the South China Sea, frankly, the Chinese fishing fleet, the Chinese coastguard and the [Navy] over match their neighbors.”
US State Department officials, however, were quick to distance themselves. "We're not aware of any plans or proposals for Japan to patrol the South China Sea," spokeswoman Jen Psaki said at a press briefing.
What's at stake for Japan?
There are compelling reasons why Japan, Asia’s second-biggest economy after China, believes it has a stake in patrolling the South China Sea. The stretch of ocean provides a tenth of the global fisheries catch and Japan is a recipient of much of the $5 trillion in cargo that passes through its crowded shipping routes.
“Certainly Japan does not have any direct territorial interests in the South China Sea, but Japan's own national security will be greatly affected by any instability and conflict there, making it a legitimate stakeholder,” says Corey Wallace, a specialist in Japanese security and defense policy at the Australia-Japan Research Center in Canberra.
Predictably, China pounced on any Japanese involvement in what many see as Beijing’s creeping appropriation of islands in the South China Sea as an attempt to foment instability.
“Countries outside the region should respect the efforts of countries in the region to safeguard peace and stability, and refrain from sowing discord among other countries and creating tensions," Chinese foreign ministry spokeswoman Hua Chunying said.
Tokyo’s ambitions appear to go beyond protecting the freedom of navigation. Helping to improve the region’s ability to monitor Chinese aerial and seaborne activity would show that it is willing to take on a heavier share of the security burden with the US, according to Mr. Wallace.
“I see the timing of bringing this up as being connected to progress on the US-Japan revised guidelines,” he says, referring to a security agreement that will be strengthened this year to coincide with the 70th anniversary of the end of the Pacific War.
Behind the issue, which appears partly to be sparked by commander Thomas’s comments, are internal differences in approach in both the US and Japan.
In the US, the bolder approach preferred by the Pentagon adds to what is already a strong US defense influence on relations with Japan. In Tokyo, the more cautions foreign ministry still calls the shots in managing the bilateral alliance.
“Ultimately, however, this will be a decision for Japan and the countries of Southeast Asia to explore more fully,” says Sheila Smith, senior fellow for Japan Studies at the Council on Foreign Relations in Washington.
Geopolitics aside, Japan would have to improve its capabilities and win the cooperation of other countries before a single plane or ship heads for the South China Sea, Ms. Smith adds.
“Basing and support for Japanese patrols would also have to be considered,” she says. “Japan would need to continue to ensure the defense of its own vast archipelago. On top of that, it would require an enhancement in its maritime security capability.”
Going forward, much will depend on whether China is willing to rein in its ambitions and recent claims to large chunks of the Pacific that have caused consternation from the Philippines to Vietnam. For now, that looks unlikely as China has apparently started reclamation work near another disputed territory, and after one of its coast guard ships recently rammed three Philippine fishing boats.
“As Chinese economic interests have grown, their interactions at sea and in and around disputed islands have made the need for a dispute resolution mechanism more urgent, but Beijing has yet to embrace the notion that these mechanisms are in its interests,” Smith says.
“So long as this continues, the nations of Asia will move towards protecting their interests unilaterally or in partnership with similarly motivated neighbors,” she says.