Hackers targeted the website of Taiwan's defense ministry, authorities in Taipei reported on Thursday, a day after a visit by U.S. House Speaker Nancy Pelosi infuriated China.

In reaction to Pelosi's visit, China was scheduled to launch a series of military exercises surrounding Taiwan on Thursday, with some activities taking place within the island's 12-nautical-mile sea and air territory, according to the defense ministry in Taipei.

This has never occurred before, and a senior ministry official characterized the proposed action as "amounting to a sea and air blockade of Taiwan."

On Thursday, China claimed Taiwan as its territory and stated that its disagreements with the self-governed island were internal.

China's Taiwan Affairs Office stated, "Our punishment of pro-Taiwan independence diehards, external forces is reasonable, lawful,"

The Chinese news agency Xinhua reported that the exercises, including live-fire drills, will commence at 04:00 GMT in six sites surrounding Taiwan.

Just hours after Pelosi departed for South Korea on Wednesday evening, unidentifiable aircraft, likely drones, flew over the Kinmen islands, according to Taiwan's military ministry.

Major General Chang Zone-sung of the army's Kinmen Defense Command told Reuters that a pair of drones entered the Kinmen region twice at about 9 p.m. on Wednesday (1300 GMT). And 10 p.m.

"We fired flares immediately to provide warnings and drive them away. After that, they reversed course. Because they entered our limited area, we dispersed them "he stated.

The heavily guarded Kinmen islands are located near the city of Xiamen, right off the southeast coast of China.

In addition, the military ministry stated that its website was temporarily taken offline due to cyber attacks late Wednesday night and was working closely with other authorities to improve cyber security as tensions with China grew.

Pelosi, the highest-ranking U.S. official to visit Taiwan in the past quarter-century, hailed its democracy and reaffirmed American assistance during her brief stopover, stressing that Chinese anger would not prevent foreign leaders from visiting Taiwan.

China summoned the American ambassador in Beijing and blocked several Taiwanese agricultural imports.

The area surrounding the U.S. Embassy in Beijing remained exceptionally secure on Thursday, as it has been all week.

Although Chinese social media users aired their anger at Pelosi, there was no evidence of significant rallies or calls to boycott U.S. products.

'Will not abandon Taiwan'

Wednesday, Taiwan scrambled jets to scare away 27 Chinese aircraft in its air defense zone, according to the island's defense ministry, adding that 22 of them violated the median line separating Taiwan and China.

In defiance of China's repeated warnings and amid rapidly deteriorating U.S.-Chinese relations, Pelosi landed with a congressional delegation on an unannounced but closely observed visit late Tuesday.

Pelosi addressed Taiwan's President Tsai Ing-wen, whom Beijing suspects of striving for formal independence - a red line for China - "Our delegation came to Taiwan to make unequivocally clear that we will not abandon Taiwan,"

This is the message we are delivering today: "Now, more than ever, America's solidarity with Taiwan is crucial, and that's the message we are bringing here today."

China believes Taiwan to be part of its territory and has never abandoned the use of force to subjugate it. The United States and the foreign ministers of the Group of Seven nations cautioned China not to use the visit as an excuse to launch a military attack against Taiwan.

"Sadly, Taiwan has been prevented from participating in global meetings, most recently the World Health Organization, because of objections by the Chinese Communist Party," Pelosi said in a statement released following her departure.

Pelosi added, "While they may prevent Taiwan from sending its leaders to global forums, they cannot prevent world leaders or anyone from travelling to Taiwan to pay respect to its flourishing democracy, to highlight its many successes and to reaffirm our commitment to continued collaboration,"