China stepped up its air and sea incursions in the Taiwan Strait from Monday evening to Tuesday morning, with 59 air strikes reported from Monday evening to Tuesday morning, and has repeatedly warned against any “external interference” in the “Taiwan issue.”

Taiwan’s Defense Ministry said 43 airstrikes were conducted across the centerline of the strait, which has long served as the de facto border between the self-ruled island and the mainland.

In addition to the fighter jets, a number of unmanned aerial vehicles, or drones, were deployed, and two balloons were also deployed.

Taiwan’s armed forces are “closely monitoring maritime and air activities” and are conducting joint operations to detect and respond to Chinese aggression, the island’s ministry said.

Beijing considers Taiwan a breakaway province that must be “reunified” with China by force if necessary.

China has launched a campaign against what it sees as Taiwan’s “separatist” efforts and has warned other countries against “interfering in the Taiwan issue.”

Chinese Foreign Ministry spokesperson Mao Ning said at a regular press briefing on Monday that Beijing “firmly opposes any form of official interaction between China’s Taiwan region and countries with diplomatic ties with China.”

“The Taiwan issue is the core of China’s core interests and it will not tolerate any external interference,” Mao said, reiterating a long-held position.

“The government of the People’s Republic of China is the sole legitimate government representing the whole of China,” the spokeswoman said. “Taiwan has never been a country, not in the past, not in the future.”

China often steps up its attacks and warnings in response to visits by American lawmakers to the island or foreign trips by the island’s leader, but this week’s activities were not a clear indicator, aside from Taiwan’s recent diplomatic efforts to strengthen cooperation with “like-minded” countries and democracies.

Taiwan immediately rejected the Chinese spokesman’s comments.

“Such clichés that contradict the facts, reverse right and wrong, and are against the will of the 23.5 million Taiwanese people are not worth rejecting,” the island’s foreign ministry said.

The ministry reiterated its position that Taiwan is a “sovereign and independent country.”

“China has no right to interfere in the exercise of any legitimate rights of a sovereign state,” it said.

Foreign ministers from the Group of 7 of the world’s most developed countries stressed “the importance of maintaining peace and stability across the Taiwan Strait” at a meeting last week.

The ministers reiterated in a statement their opposition to any unilateral attempt to change the status quo by force or coercion.