The Dongfeng-26 missile has been dubbed the "Guam killer."
"We must…cast the ideological foundation of the army's absolute loyalty to the party," Xi said.
As Trump expands relations with Taiwan, China is stepping up threats to reclaim the island by force.
The J-20 fifth-generation heavy stealth fighter brings China into a class only occupied by the world's leading military powers: the U.S. and Russia.
A Chinese military report said "the U.S. armed forces have failed to live up to Trump's expectations" due to "scandals like ship collisions, drug abuses and rapes."
A Chinese Foreign Ministry official likened U.S. complaints about China's militarization of the South China Sea to "a thief crying 'stop thief.'"
The Chinese Defense Ministry said "it is impossible to shake China's determination to safeguard its sovereignty and security interests."
"China's continued militarization of disputed features in the South China Sea only serve to raise tensions and destabilize the region," the Pentagon said.
Only the U.S., Russia and some European Union countries have such advanced stealth capabilities.
China is investing in military bases to project its power across the Asia Pacific and there's little the U.S. can do to stop it.
China has developed emerging stealth fighter technology, anti-satellite missiles and now has one aircraft carrier in operation