Watch: Pelosi says China cannot stop US officials from visiting Taiwan
Beijing began three days of missile tests near the self-governing island on Thursday, prompting fears of a military crisis in the region.
It came after US House Speaker Nancy Pelosi visited Taiwan to pledge "ironclad" support for its democratically elected government.
The Chinese regime reacted with fury, calling her visit "manic" and "irrational".
Here is everything you need to know about the tensions.
Why is Taiwan a flashpoint in US-China relations?
Taiwan has long been a flashpoint in relations between the US and China.
The island has been self-governing since nationalist forces fled there in 1949 after the communists took control of China.
Beijing considers it a "rebel province" which will eventually be "reunified" with mainland China.
It opposes any engagement by Taiwanese officials with foreign governments, which is why Pelosi's visit was so controversial.
The House Speaker is the most high-profile US politician to have visited Taiwan in 25 years.
She told Taiwanese president Tsai Ing-wen: "Today the world faces a choice between democracy and autocracy.
"America's determination to preserve democracy, here in Taiwan and around the world, remains ironclad."
China repeatedly warned Pelosi to call off her trip – which was part of a wider tour of Asia – and launched missile drills once she left.
In addition, President Joe Biden publicly raised concerns over the visit, saying the US military felt it was "not a good idea right now".
His administration does not support independent for Taiwan, which is recognised by just 13 countries.
What is the 'One China' policy?
In 1979, the US closed its embassy in Taipei in order to recognise Beijing as China's only government.
This established Washington's 'One China' policy, which remains an important part of US diplomacy in the region.
Under this principle, Washington acknowledges – but does not endorse – Beijing's claim that Taiwan is part of China.
This policy of "strategic ambiguity" allows the US to have informal diplomatic ties with Taiwan, including the sale of arms to the island.
However, Washington does not say whether it would directly intervene if China was to attack or invade the island.
How has the world responded?
China's foreign minister Wang Yi described Pelosi's visit as "manic, irresponsible and extremely irrational".
Meanwhile, Taipei's military says it was "preparing for war without seeking war".
Foreign ministers from the G7 nations, which include the UK, US and France, said China's actions "risk unnecessary escalation".
They also urged Beijing against seeking to "unilaterally change the status quo by force" in the region.
In separate comments, the UK's foreign secretary Liz Truss criticised China's "inflammatory" response to Pelosi's trip.
Russia, a close ally of China, called the visit a "clear provocation" and said Beijing "has the right to take measures to defend its sovereignty".
North Korea used Pelosi's trip to accuse the US of being "the root cause of harassed peace and security in the region".