BEIJING (Reuters) - China expressed anger on Monday after U.S. President Donald Trump signed into law measures to further bolster support for Taiwan and Tibet, which had been included in a $2.3 trillion pandemic aid and spending package. China has watched with growing alarm as the United States has stepped up its backing for Chinese-claimed Taiwan and its criticism of Beijing’s rule in remote Tibet, further straining a relationship under intense pressure over trade, human rights and other issues. The Taiwan Assurance Act of 2020 and Tibetan Policy and Support Act of 2020 both contain language objectionable to China, including U.S. support for Taiwan’s meaningful participation in United Nations bodies and regular arms sales. On Tibet, which China has ruled with an iron fist since 1950, the act says sanctions should be put on Chinese officials who interfere in the selection of the exiled spiritual leader the Dalai Lama’s successor. Speaking in Beijing, Chinese Foreign Ministry spokesman Zhao Lijian said China was “resolutely opposed” to both acts. “The determination of the Chinese government to safeguard its national sovereignty, security and development interests is unwavering,” he told reporters. The U.S. should not put the parts of the acts which “target China” into effect in order to avoid harming Sino-U.S. relations, he said, adding they were an interference in China’s internal affairs. In Taiwan, which China claims as its sovereign territory to be taken by force if needed, the government welcomed the U.S. move. “The United States is an important ally of Taiwan’s internationally, and a solid partner for sharing the values of freedom and democracy,” Presidential Office spokesman Xavier Chang said. Trump, who is due to leave office on Jan. 20 after losing November’s election to President-elect Joe Biden, backed down from his earlier threat to block the spending bill, which was approved by Congress last week, after he came under intense pressure from lawmakers on both sides of the political aisle. He signed it on Sunday evening.