Cloaked in secrecy and courting controversy, Nancy Pelosi's trip to Taiwan has been greeted with thanks in Taiwan and rage in Beijing.
So what's the beef between these two countries that share so much cultural heritage and trade? Like a lot of complicated relationships, it starts with history.
How it started
From the Dutch to the Spanish and Japanese, the island of Taiwan has bounced between nations looking to control it. China lost it to Japan after their war in the 1890s but after WWII, Japan was forced to give back its colonies - including giving Taiwan back to China.
The situation starts to get messy again during the Chinese Civil War. In 1949, the losing nationalist government fled to Taiwan and set up the Republic of China (ROC), while the mainland ended up in the control of the People's Republic of China (PRC).
In 1979, the US and PRC agreed to the 'One China' policy, which meant they would deal officially with the PRC and only have unofficial relations with Taiwan. New Zealand also adheres to the 'One China' policy.
Neither the US nor NZ recognise Taiwan as an independent nation.
China is angry with Pelosi for visiting Taiwan partly because it sees it as a violation of that 'One China' policy. US Secretary of State Antony Blinken says the policy hasn't changed. But there is the complicating factor of the Taiwan Relations Act - which says the US Congress will provide the means to help Taiwan defend itself against threats.
Jason Young, director of the New Zealand Contemporary China Research Centre, says that's partly why the US is keen to help Taiwan.
"Pelosi's message to Taiwan is that the people of the US support democracy in the region and its commitment to the Taiwan Relations Act is strong," he told 1News. "But it also reflects the poor state of US-China relations".
China has Taiwan in its sights
China's President Xi Jinping has been clear - he views Taiwan as part of China, and has not ruled out taking it by force.
Young says there's an overlay of geopolitics as Taiwan's position is strategically important too, providing a direct channel into the Pacific Ocean.
"It's the first island in an island chain off China's coast, so it's an incredibly important part of defending its shores."
Young also says while Taiwan started off as a very similar political model to China, it went through a democratisation process in the 1990s and now follows a Western style of politics.
"Taiwan has strong Chinese cultural roots so it has shown that a multi-party democracy can work within China too... so it has evolved in a different direction in the same way Singapore has."
Where NZ fits in
While New Zealand doesn't have diplomatic relations with Taiwan, we do have a "vibrant trading, economic and cultural relationship", according to the Ministry of Foreign Affairs and Trade.
"Taiwan is our eighth-largest export market… Our dairy, meat, fruit, seafood and forest products are very popular with the Taiwanese and we're their largest supplier of dairy products."
New Zealand also has a free trade agreement with China, exporting $20.1 billion worth of goods and services, according to the Ministry of Foreign Affairs and Trade.
Young says despite China being an important economic partner, our Government's response will probably be consistent with calls for dialogue and de-escalation.
"The Government will not want to be antagonistic, nor should it be. But that trade deal shouldn't change New Zealand's position on these types of issues like taking a principled position on human rights and so on."