Moscow and Beijing lashed out on Friday at Washington's new anti-Russian sanctions that also target China for the first time, warning the United States could face consequences.
The United States is "playing with fire", Russia's deputy foreign minister Sergei Ryabkov said, while Beijing voiced "strong indignation" over the move.
United in their resentment of America's global influence, China and Russia have sought in recent years to tighten up their ties and this month conducted week-long joint military drills, Moscow's largest ever war games.
On Thursday, China — which is also locked in a trade war with Washington — got caught up in the sanctions war against Russia as the United States announced a new raft of measures that would punish third countries for dealing with Moscow.
Stepping up pressure on Moscow over its "malign activities", the US State Department said it was placing financial sanctions on the Equipment Development Department of the Chinese Ministry of Defence, and its top administrator, for its recent purchase of Russian Sukhoi Su-35 fighter jets and S-400 surface-to-air missile systems.
Beijing on Friday urged the United States to withdraw sanctions or "bear the consequences".
"The US actions have seriously violated the basic principles of international relations and seriously damaged the relations between the two countries and the two militaries," said foreign ministry spokesman Geng Shuang, adding Beijing had lodged an official protest with the US.
"We strongly urge the US to immediately correct their mistake and withdraw their so-called sanctions, otherwise the US will have to bear the consequences."
US officials said it was the first time a third country has been punished under the CAATSA sanctions legislation for dealing with Russia, signalling Donald Trump's administration will risk relations with other countries in its campaign against Moscow.
Moscow said Washington was rocking global stability and said sarcastically that placing sanctions on Russia has become Washington's favourite "pastime."
"It would be good for them to remember there is such a concept as global stability which they are thoughtlessly undermining by whipping up tensions in Russian-American ties," said Ryabkov.
"Playing with fire is silly, it can become dangerous," he said in a statement.
The State Department also announced it was placing 33 Russian intelligence and military-linked actors on its sanctions blacklist.
All of them — defence related firms, officers of the GRU military intelligence agency, and people associated with the Saint Petersburg-based Internet Research Agency disinformation group — have been on previous US sanctions lists.
Twenty-eight of them have already been indicted by Robert Mueller, who is investigating election meddling by Russia.
US officials said that the US could consider similar action against other countries taking delivery of Russian fighter jets and missiles.
Turkey is in talks to buy S-400 missile systems from Russia.
Ryabkov reiterated that none of the rounds of sanctions had managed to force Russia to change its course so far.
"It appears that it has become a sort of national pastime there," he added, noting the latest round of anti-Russian measures was the 60th since 2011.
For all of Russia's seemingly upbeat rhetoric, the new measures can hurt the country's struggling economy.
Arms exports are an important source of revenue for the country and last year Russia sold more than $14 billion worth of arms overseas.
Sanctions target only Russia?
A senior US administration official, speaking on condition of anonymity, insisted the ultimate target was Russia.
"CAATSA sanctions in this context are not intended to undermine the defence capabilities of any particular country," the official said.
CAATSA, or the Countering America's Adversaries Through Sanctions Act, was passed in 2017 as a tool that gives Washington more ways to target Russia, Iran and North Korea with economic and political sanctions.
China's EDD and its director Li Shangfu became targets after taking delivery over the past year of the jets and missiles from Rosoboronexport, Russia's main arms exporter already on the US blacklist for its support of Bashar al-Assad's regime in Syria.
The US official said Washington had spent "an enormous amount of time" seeking to discourage prospective buyers of Russian arms.
The new sanctions came as the US and China are in the heat of a trade war.
The two countries will launch new tariffs on Monday, with Washington targeting $200 billion in Chinese exports and Beijing hitting $60 billion worth of American products.