Beijing's forces on Friday crossed what had been an unofficial buffer zone between China and Taiwan for decades.
From Pingtan Island, a popular scenic spot on the Chinese coast, tourists gathered to try to catch a glimpse of any military aircraft heading towards the area for military exercises.
Fighter jets could be heard flying overhead and tourists taking photos chanted: “Let’s take Taiwan back."
US Secretary of State Antony Blinken described China's military exercises - including missiles fired into Japan's exclusive economic zone - as a “significant escalation” and urged Beijing to back down.
'The entire region is now braced for what could be an extended period of instability,' ITV News Asia Correspondent Debi Edward reports
During the past week China has dispatched navy ships and warplanes, while launching missiles into the Taiwan Strait.
The action is in response to a visit by US Speaker of the House of Representatives, Nancy Pelosi, to Taiwan.
China regards the self-ruled island as its own territory to be annexed by force if necessary.
Five of the missiles fired by China landed in Japan’s Exclusive Economic Zone off Hateruma, an island far south of Japan’s main islands, Japanese Defence Minister Nobuo Kishi said.
He added that Japan protested the missile landings to China as “serious threats to Japan’s national security and the safety of the Japanese people.”
Japan's Defence Ministry later said they believe the other four missiles, fired from China’s southeastern coast of Fujian, flew over Taiwan.
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The country's prime minister Fumio Kishida said on Friday that China’s military exercises, aimed at Taiwan, represent a “grave problem” that threatens regional peace and security.
Meanwhile, China announced unspecified sanctions on Ms Pelosi for her visit earlier this week to Taiwan.
Ms Pelosi said on Friday that China will not isolate Taiwan by preventing US officials from traveling there
China's Vice Foreign Minister, Deng Li, has reiterated Beijing would “prevent the country from splitting with the strongest determination, using all means and at any cost.”
“Pelosi’s visit to Taiwan is a blatant political manipulation and a blatant and serious violation of China’s sovereignty and territorial integrity," Mr Li said.
“In response to the US-Taiwan collusion and provocation, China’s counterattack is only natural."
It comes after China said it summoned European diplomats in the country to protest statements issued by the G7 and the European Union (EU), which criticised threatening Chinese military exercises surrounding Taiwan.
The Foreign Ministry, on Friday, said Mr Li made “solemn representations” over what he called “wanton interference in China’s internal affairs".
China's Foreign Ministry said the meeting was held on Thursday night, but gave no information on which countries participated.
Earlier that same day, China cancelled a foreign ministers’ meeting with Japan to protest the G7 statement that there was no justification for the exercises.
Beijing had earlier summoned US Ambassador Nicholas Burns to protest Ms Pelosi's visit.
The speaker left Taiwan on Wednesday after meeting with Taiwan President Tsai Ing-wen and holding other public events.
She travelled on to South Korea and then Japan. Both countries host U.S. military bases and could be drawn into a conflict involving Taiwan.
The Chinese exercises involve troops from the navy, air force, rocket force, strategic support force and logistic support force, according to the official Xinhua News Agency.
They are believed to be the largest held near Taiwan in geographical terms, with Beijing announcing six exercise zones surrounding the island.
US law requires the government to treat threats to Taiwan, including blockades, as matters of “grave concern".
The drills are due to run from Thursday to Sunday and include missile strikes on targets in the seas north and south of the island.