At a briefing on Thursday, Chinese Defense Ministry Spokesman Wu Qian said that Separatist activity in Taiwan diminishes the likelihood of achieving peaceful reunification between mainland China and the island.

"The more unrestrained the separatist activities of [supporters of] Taiwan's independence are, the fewer opportunities there are for peaceful reunification," the spokesman said. He emphasized that the Chinese People's Liberation Army (PLA) will continue to improve army training and combat readiness, and will "defend national sovereignty and territorial integrity with unwavering determination."

The official noted that Beijing's fundamental approach to resolving the Taiwan issue and achieving peaceful reunification is through the principle of "one country, two systems."

These remarks come shortly after a bilateral congressional delegation from the US vowed to further support Taiwan, days after it approved a $300 million military aid package for the island.

The delegation, led by the chair of the House Intelligence and Special Operations Subcommittee, Rep. Jack Bergman, affirmed that the US will continue to support Taiwan and ensure its security and that of the region.

"This includes a strong Taiwan maritime strategy and how we can work together on shared goals to counter China on their increasingly aggressive actions in the region," he added, during his meeting with Taiwanese President Tsai Ing-wen.

Tsai Ing-wen, in return, thanked the delegation and said this would bolster US-Taiwanese relations.

Read more: Taiwan reunification is inevitable: China's Xi

Earlier this month, the government of China issued an annual report on the second session of the 14th National People's Congress, reaffirming Beijing's commitment to the One China principle. The report revealed China has boosted its national  defense budget by 7.2%, a significant rise since President Xi Jinping doubled it when he took office 11 years ago, in constant efforts to fortify the nation as a result of the Taiwan issue. The report also stated that the government will continue to oppose separatism and foreign interference in China's affairs.

The government report exhibited more robust language against Taiwan, and removed all notions of "peaceful reunification". This was not the first time China pulled a similar move, but a clear shift in tone could be regarded, signifying an increasingly firm stance toward Taiwan.