Driven by ambitions to make China a great power, President Xi Jinping is staking his political authority on a huge task: overhauling the Chinese military, which is still largely organized as it was when a million peasant soldiers mustered under Mao Zedong.
Mr. Xi wants a military that can project power across the Pacific and face regional rivals like Japan in defense of Chinese interests. To get it, he means to strengthen China's naval and air forces, which have been subordinate to the People's Liberation Army's land forces, and to get the military branches to work in close coordination, the way advanced Western militaries do.
China's military budget has grown to be the second-largest in the world, behind that of the United States, and the country has acquired sophisticated weapons systems. But Mr. Xi has told his commanders that is not enough.
"There cannot be modernization of national defense and the military without modernization of the military's forms of organization," Mr. Xi told a committee of party leaders studying military reform at its first meeting in March, Xinhua, the official Chinese news agency, reported. "There has to be thoroughgoing reform of leadership and command systems, force structure and policy institutions," he was quoted as saying.
It will not be easy. Reorganizing the People's Liberation Army, or P.L.A., will pit Mr. Xi's ambitions against the entrenched power of the land forces, with about 1.4 million troops, and he will have to manage the overhaul while ensuring that the military remains a reliable guardian of the Communist Party's hold on political power, experts said.
"Military reform is part of the larger program that Xi Jinping is putting in place to put his imprimatur on the Chinese party-state," said David M. Finkelstein, vice president and director of China studies at CNA Corporation, a research organization in Alexandria, Va., concentrating on security and military affairs.
" 'This time, we're serious' — that should be the subtext of this new tranche of reform," he said. "It will be five years before you see the fruits of it. But 10 years from now, you might see a very different P.L.A."
As it is now, the army is structured around seven powerful regional commands, originally set up to defend the country against invasion from the Soviet Union and to uphold the party's domestic control. A recasting of those military regions is at the heart of Mr. Xi's plans. The Chinese military that emerges is likely to be much more focused on confronting Japan, whose navy is generally considered to have an edge over China's, and on enforcing Beijing's territorial claims in the East and South China Seas.
That will inevitably mean transferring or decommissioning significant numbers of soldiers and bureaucrats, who can be expected to argue against Mr. Xi's plans. Underemployed or unemployed former soldiers are already a persistent source of protests in the country.
"Forces for inertia are making real military reform more difficult," said Andrew Scobell, a political scientist at the RAND Corporation in Washington who studies the Chinese military. "You've got a lot of fiefdoms, and there's the strong, disproportionate influence and power of the ground forces."
Money does not appear to be an issue, Western analysts said. "I'm not sure there would be much cost savings" from the overhaul, said Roy D. Kamphausen, a former military attaché at the United States Embassy in Beijing who is now a senior adviser to the National Bureau of Asian Research in Washington. "There seems to be a comfort level with current spending."
China spends about 2.5 percent of its gross domestic product on its military; the United States spends about 4.5 percent, Mr. Kamphausen said.
The Chinese military was already trying to accomplish a lot by 2020, at which point it hopes to have completed its mechanization and made major progress in spreading the use of information technology, said Dennis J. Blasko, another former American military attaché in Beijing.
"I see the P.L.A. undertaking a much more complex modernization process, with more components than the U.S. military after Vietnam — but without the recent combat experience, Reagan-era defense budgets, and N.C.O. corps the U.S. military had," Mr. Blasko said, referring to noncommissioned officers.
Japan and its alliance with the United States have become prime strategic interests for China, whose commanders have been referring to their country's defeat at Japanese hands in 1895 and using that humiliation as a prod for change.
"Japan's victory was a victory of its institutions," Gen. Liu Yazhou of the Chinese Army's National Defense University said in an interview with the Chinese news media last month. "The defeat of the Qing empire was a defeat of its institutions."
Mr. Xi appears well positioned to take on the obstacles to the overhaul, analysts said. Unlike his weaker predecessor Hu Jintao, Mr. Xi became chairman of the Central Military Commission at the same time he became party leader. And Phillip C. Saunders, director of the Center for the Study of Chinese Military Affairs at the National Defense University in Washington, said it was clear he had the backing of the six other members of the country's most powerful body, the Politburo Standing Committee.
Mr. Xi's efforts may be helped by the impending trial of Gu Junshan, a general whose charge sheet reads like a list of the army's most flagrant corruption problems. Mr. Kamphausen of the National Bureau of Asian Research said the selling of promotions became so widespread that General Gu's case appeared to be an especially lurid example of widespread graft.
Now, by campaigning against corruption, Mr. Xi has military commanders "so scared, they can't even park their cars in a restaurant parking lot — they send the driver somewhere else," Mr. Saunders said.
Besides the senior leadership group Mr. Xi convened in March to oversee reform, five task forces have been set up to examine specific issues, Mr. Saunders said: on training, force reduction, political indoctrination, rooting out corruption and improving the way the military manages its infrastructure.
But the biggest challenge may be loosening the grip of the ground forces.
"That's the key to everything, because at this point, if you analyze the structure of the P.L.A., the army dominates," said Nan Li, an expert on the Chinese military who teaches at the United States Naval War College in Newport, R.I. "All these services other than the ground force, their officers are marginal in the regional command structure. They are not integrated. They are on the sidelines."
Mr. Li said solving that problem would require creating separate headquarters and shifting personnel and resources to the navy, air force and missile forces, which are better able to project power abroad than the land forces are.
One basic tenet will remain: There are no signs that China's military commanders will challenge the party's control over the army, even if they privately blanch at some of Mr. Xi's demands, analysts said.
"Defense of the party is always Mission No. 1," said Mr. Finkelstein of CNA. "The officers of the P.L.A. are party members who happen to wear uniforms."