Beijing - No country, organization or individual shall imagine that they could step on or even cross the line on the Taiwan question without paying any price, foreign ministry spokesperson Mao Ning said on Monday.

Mao made the remarks at a regular press conference in response to the China's countermeasures against 12 U.S. defense corporations and 10 senior executives. It is believed that the countermeasures was China's response to U.S. sanctioning of Chinese companies for Russia-related issues and the U.S. side attending the "inauguration" of the leader of the Taiwan region.

Mao said China announced the relevant decision in the No.7 decree of the Ministry of Foreign Affairs on May 22, and China firmly opposes unilateral sanctions and long-arm jurisdiction that have no basis in international law or authorization of the UN Security Council.

"We will continue to take all measures necessary to protect our legitimate and lawful rights and interests," Mao said, adding that China urges the U.S. to deeply reflect on its behavior, face up to its responsibility for the outbreak and escalation of the Ukraine crisis, stop vilification and pressuring, and stop abusing illicit unilateral sanctions.

Mao said the Taiwan question is at the core of China's core interests, and the first red line that cannot be crossed in China-U.S. relations.

"No country, organization or individual shall underestimate the strong determination, will and ability of the Chinese government and people in defending our nation's sovereignty and territorial integrity, or imagine that they could step on or even cross the line on the Taiwan question without paying any price," she added.