Under pressure from Washington and its allies, the UN Security Council imposed a new round of punitive sanctions on North Korea on Wednesday over its fifth nuclear test in September and a series of missile launches. Yesterday, the US, Japan and South Korea announced a further tightening of their own unilateral penalties on Pyongyang.

The new round of sanctions will not only raise tensions with North Korea, but also with China, which is its strategic ally and largest trading partner. The US administration is already threatening to take action against Chinese companies that fail to fully implement the UN sanctions.

North Korea is already one of the most diplomatically and economically isolated countries in the world. No formal peace treaty was signed to end the Korean War more than 60 years ago, and so the US never established diplomatic relations with North Korea and has maintained an economic embargo.

Following the collapse of the Soviet Union in 1991, Washington’s unstated aim has been to engineer the economic and political collapse of the Stalinist regime in Pyongyang. Incapable of making any appeal to the international working class, the North Korean regime has responded with bellicose threats and a nuclear program that have only heightened the danger of a new war.

The latest UN sanctions are aimed at further crippling the North Korean economy by cutting its exports of minerals. The most significant measure is to limit the country’s annual export of coal—its largest export item—to 7.5 million tonnes or $400 million in sales. The resolution also blocks the export of North Korean zinc, nickel, silver and copper and places restrictions on the number of staff at North Korean foreign missions and their bank accounts.

Altogether, it is estimated that the new economic penalties will further reduce North Korea’s foreign exchange earnings by $800 million. If fully implemented, that figure represents a large inroad into the country’s export income. In 2015, North Korean exports brought in about $3 billion in total.

Lacking any significant trade with North Korea, the additional sanctions imposed by the United States, Japan and South Korea are targeted at individuals and corporations.

Washington added seven people and 16 entities to its blacklist, including Air Koryo, North Korea’s national airline. Tokyo banned Japanese ships that have stopped in North Korean ports from entering Japan and expanded its list to 58 of people who are blocked from reentering Japan after visiting North Korea. Seoul has expanded its blacklist by 36 individuals and 34 North Korean companies.

More significantly, the Obama administration is threatening to take action against China if it breaches the sanctions imposed on North Korea. In comments to Reuters, Danny Russel, US Assistant Secretary of State for East Asian and Pacific Affairs, said that the US would inform Beijing of any Chinese companies violating the UN resolution and expect it to act.

“If the Chinese decline or fail to act, then we’ve made absolutely clear, not only that we reserve the right to take action on a national basis under our authorities but that we will have no choice but to do so,” Russel said. Reuters reported that measures under consideration including sanctions against Chinese steel companies allegedly using North Korean coal or penalties against Chinese banks being used by North Koreans.

Russel’s remarks follow a series of warnings to China by US officials to strictly implement sanctions. US National Security Adviser Susan Rice and Secretary of State John Kerry stressed the need to choke off financial flows to Pyongyang during a meeting with Chinese State Councillor Yang Jiechi in New York on November 1.

An unnamed American official bluntly told Reuters: “If we are serious about leaning on the North, we have to go after the economy generally. As it turns out, the Chinese tolerance for North Korea misbehavior is higher than ours and that gap is not sustainable.”

The comment underscores that fact that Washington has exploited the “North Korean threat” to put Beijing under pressure and to justify its military build-up in North East Asia. As part of its “pivot to Asia” against Beijing over past five years, the Obama administration has greatly expanded its anti-ballistic missile systems that are primarily directed toward fighting a nuclear war with China.

The Chinese government has been engaged in a balancing act—attempting to force North Korea to end its nuclear programs that threaten to trigger a nuclear arms race in East Asia, while trying to ensure the Pyongyang regime does not collapse. A political implosion could allow the US and South Korea to exploit the crisis to install a pro-US regime in North Korea, on China’s northern border.

Chinese Foreign Ministry spokesman Geng Shuang said this week China has always enforced UN resolutions and would do so with the new one on North Korea. He noted that the resolution referred to the need to “avoid creating adverse consequences for North Korean civilian and humanitarian needs,” adding that the new measures were “not intended to create negative effects on normal trade.”

Geng reiterated China’s call for a return to talks on North Korea’s nuclear and missile programs. He also repeated Beijing’s opposition to US plans to place a Terminal High Altitude Area Defence (THAAD) installation in South Korea—a sophisticated anti-ballistic missile system.

The Obama administration has reportedly advised President-elect Donald Trump to make dealing with North Korea the number one foreign policy for his administration. Trump has yet to elaborate a coherent stance towards Pyongyang, but his erratic comments, right-wing militarist orientation and threats of trade war measures against China will almost certainly further inflame a highly volatile situation.

Another indication of Trump’s determination to take a belligerent attitude to China emerged yesterday when the Financial Times reported that the president-elect had spoken by phone with Taiwan’s president Tsai Ing-wen. The call was the first by an American president to his Taiwanese counterpart since formal diplomatic relations were severed in 1979.

The conversation calls into question Washington’s adherence to the “One China” policy adopted in 1972 which acknowledges the government in Beijing as the sole legitimate ruler of all China, including Taiwan. Trump’s action will provoke an angry reaction and possibly retaliation by Beijing.