BEIJING — China’s armed forces must be smaller but more capable, and if reforms are not properly carried out the military risks falling behind in its ability to wage war, Chinese President Xi Jinping said Saturday, as reported by state media.

Xi unexpectedly announced in September that he would cut troop numbers by 300,000, or some 13 percent of China’s military, currently the world’s largest at 2.3 million personnel. The cuts come at a time of heightened economic uncertainty in China as growth slows and the leadership grapples with painful economic reforms. In October, hundreds of previously demobilized soldiers protested in Beijing.

The move is part of a broader reform effort to modernize the military by moving away from the old Soviet-era command module and putting more emphasis on high-tech weapons such as stealth jets.

Last month, China showcased its Chengdu J-20 stealth fighter for the first time with a flyby over Airshow China, an industry exhibition. In 2014, the military exhibited another such craft, the Shenyang J-31. China is developing both aircraft, not just for its own defenses but as an option to sell in competition with fighters made in the United States, Russia and Europe.

Speaking at a two-day meeting on reform, Xi said that militaries must change with the times.

“Otherwise, armed forces that were strong will become outdated, or even collapse at a single blow,” Xi said in comments carried by the official Xinhua News Agency. “History and reality tells us that a military, if it falls behind the times on scale and strength, it will fall behind on war ideology and developments in waging war, maybe forfeiting strategy and right to initiate war.”

China’s military needs to put more focus on technology rather than force of numbers, Xi said.

“This is a major, inevitable change,” Xi told the meeting. “We must seize the opportunity and make breakthroughs.”

China’s government insists it has no hostile intents, but simply needs the ability to properly defend what is now widely considered to be the world’s second-largest economy.

But the nation has rattled nerves around the region with its increasingly assertive stance in the East and South China seas and an ambitious military modernization program that includes aircraft carriers and antisatellite missiles.