China and Russia have urged a peaceful solution to the nuclear crisis with North Korea, but if the U.S. invades, they're preparing to fight.
Both countries share land borders with Kim Jong Un's secretive state.
"NATO needs to take note of the enormity of China's influence," a former NATO and U.S. military leader said.
"As power is shifting away from the West toward Asia, the West's ability to influence the agenda on a global scale is expected to be reduced," the latest NATO report found.
China revealed it's building the world's fastest wind tunnel only a month after offering a glimpse of its new hypersonic DZ-ZF missile glider.
The DF-26 "Guam Killer" is China's first nuclear-capable ballistic missile that could reach the U.S. territory already threatened by North Korea.
Chinese President Xi Jinping is calling for a world-class military and leading economy, but the U.S. is suspicious of Beijing's growing ambitions in world affairs.
General Joseph Dunford, chairman of the Joint Chiefs of Staff, said China's rapid military reforms and economic growth threaten U.S. hegemony.
Chinese sailors docked in Russia with a 21-gun salute as the two countries begin sea drills in the Russian region bordering North Korea.
China's new military base is just a few miles from the only permanent U.S. outpost in Africa.
The Chinese navy closes off 15,000 square miles in the East China Sea to perform live-fire drills as the U.S.-North Korea rivalry escalates.
The base is in Djibouti, where the United States has its only permanent military base in Africa.
China's Haiyi (or "Sea Wings") unmanned underwater glider has broken world records and can instantly detect U.S. submarines in the tense South China Sea.
The largest army in the world is readying for a "potential crisis."
The U.S., Russia and China are all looking to surpass each other with military innovations such as missiles and drones that use artificial intelligence.
China and India also denied reports that 158 Indian troops were killed during recent Chinese military action in the tense border dispute.
China's military entered both Japanese and Taiwanese air identification zones in recent days, something Beijing says should be routine.
Images show planes that can detect heat waves, drones, and submarine periscopes being deployed in the South China Sea.
September's large drill in the disputed South China Sea region will be one of an annual series.
Plans for the China warship appear to live on even after the death of its designer, and it may one day change the battlefield.
Russia and China have denied media reports indicating that the nations deployed additional military forces to North Korea's borders as tensions mount with the U.S.