The sheer number of Chinese warships and warplanes patrolling a disputed East China Sea island chain threatens to overwhelm Japan's own ships and planes.

The sheer number of Chinese warships and warplanes patrolling a disputed East China Sea island chain threatens to overwhelm Japan's own ships and planes.

The imbalance could get worse for Japan.

The Senkaku islands, which are uninhabited, lie east of mainland China, northeast of Taiwan and west of Japan's Okinawa prefecture. Their location makes them strategically valuable to China and Japan. Both countries claim the islands.

In 2012, the Japanese government bought three islands in the Senkaku chain from their private owners.

Tokyo's purchase of the three islands "enraged" Beijing, according to RAND, a California think tank. The acquisition spurred China's leaders to significantly boost military sea and air operations around the Senkakus, RAND explained in its 2018 report.

By 2015, the two countries were in direct competition. China’s 2015 defense policy paper called Japan’s military modernization a “grave concern.” In its own defense policy the same year, Japan named China as a potential threat.

Around the Senkakus, military forces surged.

China's deployments were part of a broader assertion by China of its growing military might. "China seeks to overtake Japan as the dominant power in the region," the RAND report's authors wrote. "As part of that effort, China is intent on challenging Japan’s administrative control over the Senkaku islands and on demonstrating that it can exercise control in the area while avoiding escalation to a military conflict with Japan."

And the Japanese military is struggling to keep up. "The increased operational tempo has strained Japan’s ability to match the Chinese presence," RAND reported.

"By the end of 2012, the Japan Coast Guard reported that Chinese coast guard ships had intruded into Senkaku territorial waters 68 times since Sept. 11, an unprecedented number of intrusions," RAND explained.

"The campaign continued, with 188 vessels penetrating the territorial sea in 2013, 88 in 2014, 86 in 2015 and 121 in 2016.2 Since mid-2014, on average, Chinese government vessels have penetrated the territorial seas seven to nine times a month and have carried out 70 to 90 incursions in the contiguous zone—waters within which states can exercise enhanced jurisdiction but that do not constitute sovereign territory like those of a territorial sea."

A similar competition played out in the air, the RAND researchers found.

"On Dec. 13, 2012, a Y-12 aircraft belonging to the State Oceanic Administration, a Chinese state entity, made the first-ever unauthorized intrusion into Japanese-claimed airspace in the then-45-year history of record keeping on these issues, passing by the Senkaku islands."

Meanwhile in November 2013, China announced the formation of an East China Sea Air Defense Identification Zone stretching into the East China Sea over the Senkakus. The zone overlaps with overlaps with the I.D. zones of Japan and other neighboring countries.

"According to a Chinese Ministry of National Defense statement, all aircraft entering the zone must identify themselves to Chinese authorities and are subject to emergency military measures should they fail to abide by the rules governing the ADIZ," RAND reported.

The Japanese ministry of foreign affairs described Beijing's establishment of an ADIZ as a "profoundly dangerous."

Starting in 2012, China dramatically increased the number of military sorties flying near Japan. "Fighter planes from both countries now routinely fly in close proximity to one another, raising the risk of miscalculation and dangerous crises," RAND explained.

On paper, China has at least one advantage in the aerial competition, according to RAND. "Nationwide, China has 1,700 fighter aircraft, while Japan has about 288."

"China’s large inventory of fighter aircraft has enabled it to fly frequent missions near Japan, straining the limited resources of the Japanese Air Self-Defense Force," the researchers explained. "Fiscal year 2016 saw the largest number of JASDF scrambles—1,168 in total—73 percent of which were against Chinese aircraft primarily flying near and around the Senkaku island chain and the East China Sea."

Much of Japan's effort to counter China's incursions is diplomatic in nature. "Japan has sought stronger strategic relationships in the Indo-Pacific region, including with Australia, India and Southeast Asian states such as The Philippines and Vietnam," according to RAND.

"While not explicit, this networking strategy gives Japan an ever-growing base of diplomatic support to rely on when countering Chinese provocations. Some of these relationships have seen collateral improvements in operational ties, as well."

But Japan’s most significant efforts to counter China are military. Tokyo's spending on its armed forces grew from $41 billion in 2012 to $43 billion in 2017 and $47 billion in 2019.

The extra money has paid for a expansions and improvements across the Japanese military, including "new intelligence, surveillance and reconnaissance and anti-ship-warfare capabilities; growth in the submarine and destroyer fleet; the establishment of an amphibious rapid deployment brigade; the stationing of [Self-Defense Forces] assets on islands close to the Senkakus and the establishment of an air wing in Okinawa," RAND found.

"It has also increased the Japan Coast Guard budget and established a coast guard patrol unit tasked specifically with patrolling the Senkaku Islands."

The coast guard is the lead agency responding to Chinese incursions. Its budget "has grown in recent years, with an increasing amount dedicated solely to Senkaku island defense," according to the think tank.

The Japanese Air Self-Defense Force has reorganized and re-equipped in an effort to match China's own aerial surge. In April 2014, the JASDF stood up the 603rd Squadron at Naha Air Base on Okinawa. The squadron consists of four E-2C Hawkeye airborne early warning aircraft.

In January 2016, the air force added a second squadron of F-15 fighters at Naha.

These fighters handle most of the daily interceptions of Chinese planes. But not without cost. "The increased demand on the JASDF means that the frequency with which these aircraft require such inspections and maintenance is increasing," RAND warned.

"Likewise, the increased incursions into Japanese airspace are negatively impacting JASDF pilot training. JASDF personnel are required to log a set number of hours to obtain qualifications for different skills. Because of the finite pilot training time being devoted to relatively mundane interception responses, there is an impact on training for other missions."

The workload could get worse for Japanese crews as the air force replaces older F-2, F-4 and F-15 fighters with new F-35s. By late 2018 Tokyo had ordered 141 F-35s. "Given anticipated retirements of the F-2 and F-15 airframes, Japan could face a reduced inventory of fighter aircraft, even as it awaits delivery of a limited number of F-35s."

RAND cautioned that, in light of "long-term trends in acquisitions and China’s quantitatively superior inventory," Tokyo's reforms "may not be sufficient to enable Japan to keep pace over the longer term" as the two countries compete over the Senkakus.

David Axe edits War Is Boring . He is the author of the new graphic novels MACHETE SQUAD and THE STAN.