BEIJING—Soon after taking over as Communist Party and military chief, Xi Jinping launched a series of speeches referring to "The China Dream."

It was music to the ears of Col. Liu Mingfuof the People's Liberation Army.

Three years ago, the former professor at its National Defense University wrote a book of the same name, arguing that China should aim to surpass the U.S. as the world's top military power and predicting a marathon contest for global dominion. The book flew off the shelves but was pulled over concerns it could damage relations with the U.S., according to people familiar with its publication.

The day after Mr. Xi's first "China Dream" speech, however, Col. Liu's publisher called to say he had gotten approval to launch a new edition. Now, it is on display in the "recommended books" section of a state-run bookstore.

"I don't know if he read the book, but he has sent a strong message," Col. Liu said in an interview at his apartment here, leaping to his feet with excitement to leaf through letters of support. "He could have grasped the economy, or some social issues, but instead he grasped the military."

As Mr. Xi prepares to add Chinese president to his other titles on Thursday, during a parliament meeting that caps a once-a-decade leadership change, "The China Dream" has become his signature. Officially defined as the rejuvenation of the Chinese nation, it in some ways echoes previous leaders dating back to the Qing Dynasty's collapse in 1912. But Mr. Xi is making the idea his own by giving it a strikingly military flavor.

"This dream can be said to be the dream of a strong nation. And for the military, it is a dream of a strong military," Mr. Xi told sailors in December on board the Haikou, a guided-missile destroyer that has patrolled disputed waters in the South China Sea. "To achieve the great revival of the Chinese nation, we must ensure there is unison between a prosperous country and strong military."

Mr. Xi has also made high-profile visits to army, air force, space program and missile command facilities in his first 100 days in office, something neither of his two immediate predecessors did. He has taken personal control of China's military response to a newly inflamed territorial dispute with Japan. And he has launched a campaign to enhance the armed forces' capacity to "fight and win wars."

All this leads many diplomats, party insiders and analysts to believe Mr. Xi is casting himself as a strong military leader at home and embracing a more hawkish worldview long outlined by generals who think the U.S. is in decline and China will become the dominant military power in Asia by midcentury.

In doing so, they say, Mr. Xi is setting the stage for a prolonged period of tension between China and its neighbors, as well as for a potentially dangerous tussle for influence with a U.S. that is intent on reasserting its role as the dominant Pacific power.

He has even set a precise date for the fulfillment of his dream: 2049, the 100th anniversary of the Communist takeover of China.

No doubt Mr. Xi has a domestic political agenda. As the son of a revolutionary leader, he has strong family ties to the military and a keen appreciation for its role in elite Chinese politics. In another speech, he made clear he believes the Soviet Union collapsed largely because the Soviet Communist Party lost command of the military.

Some believe Mr. Xi is trying to build support among China's powerful generals as a prelude to launching potentially disruptive economic and other reforms, including moves to curb corruption within the military itself. Others suspect he is trying to distract attention from problems that could derail Chinese growth, especially official corruption and abuse of power, an issue highlighted by the Bo Xilaiscandal last year.

More broadly, Mr. Xi is determined to set himself apart from his predecessor, Hu Jintao, who was popularly viewed as relatively weak and colorless, say party insiders, family friends, diplomats and analysts.

Whatever his domestic goals, Mr. Xi's military posturing represents a clear break with the past that has potentially profound implications for China's foreign and defense policies.

"I think this reflects Xi's mind-set, his view of China's strength and relations with the outside world," said Li Mingjiang, an assistant professor and China security-policy expert at Nanyang Technological University in Singapore. "Given his close personal ties, a lot of the information and policy suggestions he gets come from the military."

For three decades, the foundation of China's international relations has been the principle of taoguang yanghui—"hiding capabilities and biding one's time"—which was promoted by the late leader Deng Xiaoping.

Jiang Zemin, who became party and military chief in 1989 but had little authority over the generals until Mr. Deng's death in 1997, eventually won them over with defense-spending increases but kept them focused on building the capacity to defend borders and retake Taiwan.

After Mr. Hu became party chief in 2002, he kept a low military profile, not least because Mr. Jiang remained commander-in-chief until 2004. He focused on China's "peaceful rise," a term later toned down to "peaceful development." Although Mr. Hu encouraged the military to take on broader responsibilities, such as cybersecurity, he stressed their defensive nature.

By contrast, Mr. Xi has quickly asserted his authority over the 11-man Central Military Commission, on which he is the sole civilian. Among his first moves was to issue orders for the armed forces to focus on "real combat" and "fighting and winning wars," suggesting to many observers preparation for conflict beyond China's borders.

Mr. Xi also has added a qualification to Mr. Hu's signature foreign-policy idea: "We will stick to the road of peaceful development," he recently told the Politburo, according to the Xinhua news agency, "but we absolutely will not abandon our legitimate rights and interests, and absolutely cannot sacrifice core national interests." In China, the "core interests" term is taken to mean issues of sovereignty over which China would be prepared to go to war.

Mr. Xi has backed up his words with actions, overseeing a military response to the territorial dispute with Japan that included scrambling Chinese fighter jets and, according to Japanese and U.S. officials, locking weapons-guiding radar onto a Japanese ship and helicopter. Chinese officials deny those incidents.

"The Chinese are making up their own rules," said one U.S. military official, who described the radar incidents as "a serious escalation."

Mr. Xi's words and actions have played well with the Chinese public, as well as with military hawks like "China Dream" author Col. Liu. He and other outspoken officers don't reflect official policy but play an important part in molding public opinion, and do reflect the mind-set of more senior commanders, analysts say.

Col. Liu's book has a preface by Gen. Liu Yazhou, the political commissar of the National Defense University. "In my opinion," the general writes, "the competition between China and the U.S. in the 21st century should be a race, that is, a contest to see whose development results are better, whose comprehensive national power can rise faster, and to finally decide who can become the champion country to lead world progress."

Gen. Liu is among a small group of officers who have met regularly in private with Mr. Xi and helped to shape his strategic worldview, say people familiar with the matter.

For three years or so, many U.S. and Asian officials have attributed China's more assertive behavior, especially on territorial issues, partly to military hawks exerting pressure on a weak civilian leadership through the media, academia and informal lobbying channels.

Now those U.S. and Asian officials' concern is that Mr. Xi, while establishing clear authority over China's generals, has endorsed the more muscular approach to international relations, and a more prominent role for the military in China's development. Since his speech aboard the destroyer, China's military newspapers have been peppered with references to the "dream of a strong military" and the need for "combat readiness."

The PLA's General Staff Office published an article in Qiushi, the official journal of the party's Central Committee, in February that said: "History and reality show us that what determines the political and economic pattern of the world is, in the final analysis, a comparison of great powers' strength, and ultimately depends on force."

The PLA has also issued instructions for training to focus on real combat. Recently it for the first time published a schedule of exercises for the year, which will consist of 40 drills involving joint air-land combat and live fire operations on the open sea.

"Make no mistake, the PRC Navy is focused on war at sea and about sinking an opposing fleet," said Capt. James Fanell, deputy chief of staff for intelligence and information operations for the U.S. Pacific Fleet, at the U.S. Naval Institute in January. "In terms of their ultimate goals, they write a lot about national rejuvenation—restoration of China's rightful place. Well, we have to say: What does that mean? Where were they when they were back in their rightful place?"

For PLA commanders, according to many analysts, the dream of a strong military means securing the defense-spending increases needed to fund costly weapons programs such as aircraft carriers and stealth fighter jets, even as economic growth slows over the next decade.

The PLA has been focused for much of the past decade on developing and deploying the weapons it believes it needs to deny U.S. forces access to waters around China's shores. But while wary of entering an arms race with the U.S., it is increasingly preoccupied with enhancing capabilities to operate farther afield and establishing China as a maritime power.

"Even a blind man could see there is going to be a butter-versus-guns debate not far down the road," said Kenneth Lieberthal, an expert on Chinese politics at the Brookings Institution in Washington.

Many Chinese and foreign analysts see Mr. Xi's military stance, especially regarding the territorial dispute with Japan, as a direct response to the U.S. "pivot" toward Asia.

The short-term aim, those analysts say, is to discourage countries that have territorial disputes with China from feeling emboldened by the U.S. strategy of focusing more on Asia. Longer term, the goal is to convince the U.S. that the strategy is unsustainable, given financial pressures on the Pentagon and China's expanding power.

"China's strength can play a positive role in the region," said Xu Guangyu, a retired PLA general and now a senior researcher at the China Arms Control and Disarmament Association. "It's a strategic mistake for the U.S. to rely on Japan for its rebalancing in Asia."

One U.S. military adviser said Chinese military strategists see China becoming the dominant power in Asia by midcentury, by which time they believe the world will be divided into spheres of influence dominated by at least four great powers: China, the U.S., the European Union and Russia.

That view also appears to be reflected in Mr. Xi's main foreign-policy initiative, which is a proposal to redefine China's relationship with the U.S. as one between equal "great powers."

U.S. officials and analysts are still waiting for details about the proposal. But many foreign governments fear it is an attempt to curb U.S. influence in Asia, in much the way the U.S. sought to restrict European meddling in the Americas with the Monroe Doctrine in the early 19th century.

War remains an unlikely prospect, say most observers. Even Col. Liu, whose next book is titled "Why the People's Liberation Army Can Win," didn't predict war in "The China Dream," seeing instead a protracted competition that Beijing is destined to win.

Lee Kuan Yew, the former Singaporean leader, has said that Chinese leaders recognize they can't confront the U.S. militarily until they have overtaken it in terms of the development and application of technology. Nonetheless, he says he is sure they aspire to displace the U.S. as the leading power in Asia.

"The 21st century will be a contest for supremacy in the Pacific because that is where the growth will be," Mr. Lee was quoted as saying in a recently published book. "If the U.S. does not hold its ground in the Pacific, it cannot be a world leader."

—Brian Spegele and Carlos Tejada contributed to this article.

Write to Jeremy Page atjeremy.page@wsj.com