They say that whether this is the end of it, or how far it goes, would depend on China's reaction to the new sanctions, and whether they start to do more against North Korea.
The timing and scope of the United States action will depend heavily on how China responds to pressure for tougher steps against North Korea when United States and Chinese officials meet for a high-level economic dialogue in Washington on Wednesday, the administration sources told Reuters.
"What China enforces is United Nations resolutions, not the domestic law of certain countries", Shuang said, adding that sanctions represented "abandoning one's benefactor upon achieving one's goal".
He's blasted the Asian superpower and even asked President Xi Jinping face-to-face to take a tougher stance on North Korea's missile and nuclear defense program.
Sino-US relations have soured in recent weeks as President Donald Trump has urged Beijing to step up diplomatic and economic pressure on North Korea over its nuclear and missile programmes.More news: Evidence Suggests Russian Intelligence Pipeline To Trump Campaign
Song continued that "neighboring countries surrounding the Korean Peninsula" were in an "age of limitless competition" seeking their own national interests, which is why South Korea needed to build more military muscle to "suppress any threat from North Korea and become a reciprocal bridge to countries nearby".
One official said more than 10 Chinese firms could be targeted, much more than Trump reportedly shared with Xi when he hosted him at the president's Mar-a-Lago club in Florida back in April.
The new measures would target Chinese small-and-medium sized financial institutions and shell companies suspected of "funneling cash" into Pyongyang's nuclear and missile programs. This is going to mean Chinese banks.
"Such actions are obstructing cooperation between China and the U.S. and lead to questions about the real intentions of the USA side", according to a transcript of his remarks from the Chinese embassy.
China insisted Thursday it was upholding UN sanctions on North Korea despite a jump in its trade with the nuclear-armed nation that comes amid growing USA calls for Beijing to rein in its neighbour.