HONG KONG — China is moving ahead with the development of a new and more capable generation of intercontinental ballistic missiles and submarine-launched missiles, increasing its existing ability to deliver nuclear warheads to the United States and to overwhelm missile defense systems, military analysts said this week.

Over all, China’s steady strengthening of its military capabilities for conventional and nuclear warfare has long caused concern in Congress and among American allies in East Asia, particularly lately as China has taken a more assertive position regarding territorial claims in the East China and South China Seas.

The Global Times, a newspaper directly controlled by the Chinese Communist Party, reported Wednesday that China was developing the capability to put multiple warheads on intercontinental ballistic missiles, or ICBMs. But the newspaper disputed a report in Jane’s Defense Weekly that the latest Chinese ICBM, the Dongfeng-41, had been tested last month.

A Pentagon spokesman asked to comment did not directly address the potential new Chinese missile capability, but said the United States “remains committed to maintaining healthy, stable, reliable and continuous military-to-military relations with China and regularly discusses ways to reduce tensions and build trust in the region.”