As tensions between Beijing and Washington escalate, China warned Tuesday that the US will "pay the price" if US House Speaker Nancy Pelosi visits Taiwan.

"The US side will bear the responsibility and pay the price for undermining China's sovereign security interests," Foreign Ministry Spokeswoman Hua Chunying said at a regular press briefing.

Beijing pledges to deliver harsh response

China will take decisive efforts to preserve the national sovereignty and territorial integrity of US House Speaker Nancy Pelosi's trips to Taiwan, said Chinese Foreign Ministry spokesperson Hua Chunying on Tuesday, ahead of Pelosi's likely visit.

Read next: China sorties warplanes in Taiwan Strait amid tensions

"We pay close attention to Pelosi's route, and if the US acts without regard to the opinions of others, China will certainly take decisive and tough measures to protect sovereignty and security interests," Hua told a briefing.  

Simultaneously, the Ambassador stated that China and the US maintain close touch at all levels and through multiple channels.

Read next: US military assets deployed ahead Pelosi's potential visit to Taiwan

China not ready for discussions on new START treaty: FM

In another context, China is not prepared to participate in discussions on the New START (Strategic Arms Reduction Treaty) with the US and Russia because its nuclear stockpile is far smaller, said Foreign Ministry Spokeswoman Hua Chunying on Tuesday.

"China's nuclear arsenal is not on the scale of the US. It is unfair and irrational to ask China to join the multilateral disarmament process at this stage," Hua told a briefing.

Read next: Medvedev skeptical about US proposal to return to new START extension

Some US politicians openly ‘play with fire’ when it comes to Taiwan issue

Some US politicians are openly playing with fire when it comes to the Taiwan issue in pursuit of their own interests, Chinese Foreign Minister Wang Yi said on Tuesday ahead of a possible visit of US House Speaker Nancy Pelosi to Taiwan later in the day.

"Some politicians in the US are openly playing with fire in regard with the Taiwan issue in pursuit of their own interests," the Minister said in a statement.

The US is violating its obligations on Taiwan, which further undermines confidence in Washington, the minister added.