China’s government said Monday that it will boost its defense spending by 8.1 percent this year, the biggest increase in three years, even as it insists that it poses no threat to other countries.

President Xi Jinping is attempting to modernize China’s military, vowing to turn it into a “world-class force” that is capable of fighting and winning wars.

China’s defense spending is still about a quarter of U.S. levels, but its long-term growth has rattled some neighboring countries, especially given Beijing’s more assertive enforcement of territorial claims.

In a keynote address to an annual meeting of the National People’s Congress, Premier Li Keqiang said the country faced “profound changes in the national security environment,” necessitating a stronger military.

As a proportion of the economy, China spends about 1.9 percent of its gross domestic product on the military, compared with about 3.3 percent for the United States, according to the Stockholm International Peace Research Institute. The 2018 spending increase would outpace China’s economic growth.

Zhang Yesui, a vice foreign minister and spokesman for the National People’s Congress, said China’s defense spending was still lower than that of other major countries on a per capita basis.

“China is committed to a path of peaceful development, and China pursues a defense policy that is defensive in nature,” he said at a news conference. “China’s development will not pose a threat to other countries.”

But Andrew Erickson, a professor at the Naval War College’s China Maritime Studies Institute in Newport, R.I., said it was revealing that military spending would outpace China’s economic growth.

“This shows that Xi’s grand strategy to ‘make China great again’ includes not only a ‘China dream’ generally but also a ‘strong military dream’ specifically,” he said.

Erickson said China has the world’s second-largest defense budget after the United States, enabling it to achieve the biggest and fastest shipbuilding expansion in modern history; the world’s largest navy, coast guard and maritime militia by number of ships; and the world’s largest conventional ballistic and cruise missile force.

In its National Defense Strategy issued at the end of last year, the Pentagon accused China and Russia of being “revisionist powers” that want to shape the world in accordance with their authoritarian models of government and pose the central challenge to U.S. prosperity and security. It also accused China of seeking “Indo-Pacific regional hegemony,” of intimidating its neighbors while militarizing the disputed waters of the South China Sea and of wanting to establish global preeminence at the expense of the United States in the longer term.

But Chinese officials and analysts played down the threat.

Zhang said the uptick in defense spending is partly to compensate for past insufficient spending and is mainly being used to upgrade equipment, better the lives of service members and improve training conditions for troops.

Song Xiaojun, a Beijing-based military commentator, said the spending increase was partly to make up for personnel laid off as part of a recent reduction in the armed forces by 300,000 troops, while Maj. Gen. Luo Yuan, vice president of the China Strategic Culture Promotion Association, said the budget was normal for maintaining the army and did not signify a preparation for war.

“China has not had any wars in the past 30 years,” he said. “It’s building its military to ensure its own safety, so foreign powers don’t need to worry.”

Ni Lexiong, a military expert at the Shanghai University of Political Science and Law, said the increase was modest in the face of rising costs, tensions on the Korean Peninsula and a border standoff with India. “Considering such a situation, this symbolic increase is equal to no increase,” Ni said.

Shirley Feng and Liu Yang contributed to this report.