United recently won approval from the US Department of Transportation to operate a new nonstop flight from Beijing to Washington, a route that is estimated to be worth US$200 million a year.
The US airline said details on its flight plans will be announced next month.
"We are sure to expand cooperation with Air China through codeshare or co-marketing in the future," said a spokesman for United in Beijing.
Like its domestic counterparts, Air China has been suffering losses on Sino-US routes as a result of appreciation of the yuan and a weaker brand compared with their formidable US rivals.
Air China has just invested 688 million yuan (US$86 million) to upgrade its first-class and business-class facilities on its Sino-US routes and improve its online booking system, Rao said.
China Eastern Airlines which operates aShanghai-New York and Shanghai-Los Angeles service, said it will seek to expand its advantages on Sino-Japan and Sino-Korean routes to reduce any competitive effects from Air China's latest moves.