Beijing has warned the US must "bear responsibility for the consequences" if Washington doesn't withdraw new sanctions on China for procuring military equipment from Russia.
The US government imposed sanctions on the Chinese military on Thursday for buying ten SU-25 fighter jets and S-400 surface-to-air missile systems from Russia, in breach of a sweeping US sanctions law punishing Moscow for meddling in the 2016 US election.
In response, "China expresses strong indignation at these unreasonable actions by the US side and has already lodged stern representations," said Foreign Ministry spokesman Geng Shuang.
"We strongly urge the US side to immediately correct the mistake and rescind the so-called sanctions; otherwise the U.S. side will necessarily bear responsibility for the consequences," he said, without giving details.
China has cozied up to Russia lately at a time when both nations have been targeted by the US. Bilateral relations have been so successful that China was invited to take part in military exercises in Russia earlier this month, the country's largest since the Cold War and the first including a country from outside the former Soviet bloc.
Chinese President Xi Jinping and Russian President Vladimir Putin also cultivated a rather public friendship. Xi and Putin have met several times, most recently at an annual economic forum in Vladivostok that occurred alongside the joint war games. The pair have enjoyed traditional foods together and Putin even recalled celebrating his birthday once with Xi. In 2017, Xi was award Russia's highest state order, an occasion commemorated by Putin hanging an elaborate medallion around Xi's neck. The following year Xi reciprocated by presenting Putin with a similar high order of friendship in the form of a giant gold necklace.
As these new sanctions show, close relations with Russia means China could suffer collateral damage as the US continues to target Moscow, on top of escalating trade tensions with Washington.
One US administration official, who briefed reporters on condition of anonymity, said the sanctions imposed on the Chinese agency were aimed at Moscow, not Beijing or its military, despite an escalating trade war between the United States and China.
Despite China essentially taking a hit for Russia, security analysts in Asia think the sanctions could further boost ties between Moscow and Beijing.
"The imposition of US sanctions will have zero impact on Russian arms sales to China," said Ian Storey, of Singapore's ISEAS Yusof Ishak Institute.
"Both countries are opposed to what they see as US bullying and these kind of actions will just push Beijing and Moscow even closer together," he said, adding that Moscow needed Chinese money and Beijing wanted advanced military technology.
Collin Koh, a security analyst at Singapore's S Rajaratnam School of International Studies, said the sanctions would do little to counter the evolving research and development relationship between China and Russia.
Indeed, for now, Geng said China would continue to work with Russia to promote strategic cooperation at an even higher level.
China relies less on large big-ticket purchases from Russia, but Chinese defense industries are seeking expertise from Russia and former-Soviet states to plug knowledge gaps, he said.
The sanctions target China's Equipment Development Department, the military branch responsible for weapons and equipments, and its director Li Shangfu for engaging in transactions with Russia's main arms exporter, Rosoboronexport.
Trump has insisted there was no collusion with Russia. Moscow denies any effort to meddle in US politics.
They also block the Chinese agency and Xi from applying for export licenses and participating in the US financial system, and adds them to the Treasury Department's list of specially designated individuals with whom Americans are barred from doing business.
The US blacklisted another 33 people and entities associated with the Russian military and intelligence, adding them to a list under the 2017 law, known as the Countering America's Adversaries Through Sanctions Act, or CAATSA.