Chinese President Xi Jinping vowed to "reunify" with Taiwan, by force, if necessary, one day before the 75th anniversary of the founding of the communist People's Republic of China.
The Chinese leader made his remarks at a state banquet on Monday and used his speech to reiterate his objective of achieving "complete reunification of the motherland."
"It's an irreversible trend, a cause of righteousness and the common aspiration of the people," Xi told thousands at the Great Hall of the People in Beijing, CNN reported, citing state news agency Xinhua. "No one can stop the march of history."
Despite having never controlled it, China's Communist Party claims the self-governing democracy of Taiwan as its own and has pledged to ultimately rule the island nation.
Many people on the island see themselves as Taiwanese and are not in favor of being taken over by Communist China.
At the end of the Chinese civil war in 1949, the communists seized power in Beijing and founded the People's Republic of China on Oct. 1. The defeated nationalists fled to Taiwan and moved the Republic of China's seat from the mainland to the island's capital of Taipei.
Chinese leaders have continually vowed to take control of Taiwan one day, but Xi's aggressive rhetoric and posturing have fueled concerns across the strait and around the world about the increasing likelihood of a military clash.
"Taiwan is China's sacred territory," Xi reportedly told the more than 3,000 banquet attendees. "Blood is thicker than water, and people on both sides of the strait are connected by blood."
The head of the Chinese Communist Party also called for the promotion of "spiritual harmony of compatriots on both sides," as well as expanded economic and cultural exchanges with Taiwan.
"[We must] resolutely oppose 'Taiwan independence' separatist activities," Xi said.
Tensions have increased since Taiwan's President Lai Ching-te was inaugurated in May. Lai has called on China to cease intimidating Taiwan, while Beijing has labeled Lai a "dangerous separatist."
Taiwanese officials say China has ramped up its military presence around the island in recent months, including holding drills in May that Beijing said were a test of its ability to "seize power."
Taiwan's Defense Ministry said on Sunday it was on alert after detecting "multiple waves" of missiles being fired in the inland regions of Inner Mongolia, Gansu, Qinghai, and Xinjiang.
In a statement obtained by CNN, the ministry said that Taiwan's air defense forces have "maintained a high level of vigilance and strengthened their alert."