China has again lodged a protest with the US, saying that its new sanctions being planned for the Democratic People's Republic of Korea may include measures on Chinese entities and financial institutions involved.

In her testimony before the US Senate on Tuesday afternoon, Susan Thornton, acting US assistant secretary of state for East Asian and Pacific affairs, said, "We will step up efforts to sanction individuals and entities enabling the DPRK regime, including those in China."

"China must exert its unique leverage over the DPRK," she said.

On Tuesday, the US House of Representatives overwhelmingly passed a bill for new sanctions on Russia, Iran and the DPRK. The legislation must go to the Senate, which may favor a separate bill on the DPRK, before being sent to US President Donald Trump.

"China always opposes unilateral sanctions outside the framework of the United Nations Security Council, especially the 'long-arm jurisdiction' imposed on Chinese entities and individuals by other countries in accordance with their domestic laws," Foreign Ministry spokesman Lu Kang said when asked to comment on Thornton's words on Wednesday.

He said China has been comprehensively and accurately implementing the Security Council resolutions and fulfilling its international obligations.

"If any Chinese companies and individuals are found to have violated the Security Council resolutions, we will investigate and deal with them in accordance with our laws and regulations," said Lu, who was the deputy chief of mission at the Chinese embassy in Washington before assuming the current post in 2015.

"What the US has done will not help solve the problem or improve mutual trust and cooperation between China and the US on the non-proliferation issue," Lu added.

During her testimony at the Senate Foreign Relations Committee Subcommittee on East Asia, the Pacific and International Cybersecurity Policy, Thornton said the US has called on all UN member states to fully implement the commitments they made regarding DPRK; urge countries to suspend or downgrade diplomatic relations with DPRK; and asked all countries to cut trade ties with Pyongyang as a way of increasing DPRK's financial isolation.

Much of her testimony focused on increasing pressure and sanctions on the DPRK.

"Sanctions, it seems to me at this moment, are a very long road that leads to nowhere," Leon Sigal, director of the Northeast Asia Cooperative Security Project at the Social Science Research Council, told lawmakers on Tuesday in a panel right after Thornton's testimony.

Sigal believes restarting negotiations is imperative. "Pressure without negotiations has never worked in the past with Pyongyang and there is no reason to think it will work now," he said.

"With that in mind, legislation now under consideration should not immediately trigger sanctions, but provide for at least a three-month implementation period to allow time for talks to resume," he added.

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