War tensions between the US and China are continuing to rise amid the visit of US Speaker Nancy Pelosi to Taiwan - but where does the conflict originate?
In a show of strength, Chinese warplanes have flown close to Taiwan's maritime border, while the US Navy has deployed four warships to the Taiwan Strait.
In Fujian, the region closest to Taiwan, flights to the area have been cancelled and military equipment has been deployed there while military boats and trucks can be seen being carried through Xiamen in China.
Arguments over the territory have lasted decades, ever since the Chinese Communist Party (CCP) took control of mainland China in 1949 following the civil war.
It has continued to argue that Taiwan, where the opposing nationalist party fled to, is part of its territory.
Taiwan, which brands itself the Republic of China (ROC), has remained self-ruled, but the CCP views reunification with Taiwan as a key part of its Communist ideology and the country's identity.
This is also known as the "one China" policy.
The CCP has repeatedly insisted it was willing to decide the future of Taiwan with military strength and "will take resolute and vigorous countermeasures", such is the strength of feeling among the party and the country's leader Xi Jinping.
A spokesman for the Chinese Foreign Ministry, Zhao Lijian, said on Monday: "We once again sternly warn the US side that China stands at the ready and the Chinese People’s Liberation Army will never sit idly by."
China is therefore concerned that the visit of a top US official is a showing of support for the island's continued self-governance away from the mainland.
Support for Taiwan among Congress is high, so China will view Pelosi's visit with concern.
Further complicating matters is the independence of the US Congress from the White House. Pelosi's visit is not on the orders of Biden, who has said "the military thinks [the trip is] not a good idea."
The visit of the speaker comes amid what was already a war of words between China and the US.
In May, Biden insisted the US will defend Taiwan if it is attacked, pulling the de facto NATO leaders away from the previous policy of "strategic ambiguity."
Biden said the US continued to agree with the One China policy, but would not accept military aggression toward Taiwan.
He said: "That's the commitment we made. We agree with a One China policy.
"We've signed on to it and all the intended agreements were made from there. But the idea that, that it can be taken by force, just taken by force, is just not, is just not appropriate."
Very few countries formally recognise Taiwan as to do so would mean breaking off diplomatic relations with China altogether.
The ones that do have limited influence on world affairs and include the likes of Paraguay, the Vatican City, Saint Vincent and the Grenadines and Nauru.
More powerful countries like G7 members the UK, US and Canada have unofficial diplomatic relations with Taiwan, but formally recognise the CCP-controlled state, or People's Republic of China (PRC).
The belief that Taiwan's existence is naturally Chinese in the CCP's eyes stems from historical periods control of the island around 100 miles away from mainland China.
It is considered one of the 'Three Ts', considered the most contentious issues in Chinese politics alongside the covered-up protest at Tiananmen square in 1989 and resistance to Tibetan independence.
