China has summoned the Japanese ambassador in Beijing over Prime Minister Sanae Takaichi's comments on Taiwan.
China and Japan have been locked in an escalating war of words this week, set off by Takaichi's suggestion that Japan could respond with its own self-defense force if China attacked Taiwan.
Both countries' foreign ministries have lodged serious protests with each other. A Chinese diplomat also made a comment which some interpreted as a threat to behead Takaichi.
The spat touches on the historical animosity between China and Japan, as well as longstanding 'strategic ambiguity' on the sovereignty of self-governed Taiwan.
Here's what else you need to know about it:
What happened? A timeline
The current tensions were sparked at a parliamentary meeting in Japan last Friday, when an opposition lawmaker asked Takaichi what circumstances surrounding Taiwan would count as a survival-threatening situation for Japan.
'If there are battleships and the use of force, no matter how you think about it, it could constitute a survival-threatening situation,' Takaichi responded.
A 'survival-threatening situation' is a legal term under Japan's 2015 security law, referring to when an armed attack on its allies poses an existential threat to Japan. In such a situation, Japan's self-defense forces can be activated to respond to the threat.
Takaichi's remarks drew immediate ire from Beijing, with China's foreign ministry describing them as 'egregious'.
On Saturday, Xue Jian, China's consul general in the Japanese city of Osaka, reshared a news article about Takaichi's parliamentary remarks on X. But he also added his own comment that 'the dirty head that sticks itself in must be cut off'.
While the intent of Xue's remarks 'may not be clear', they were 'highly inappropriate', Japan's chief cabinet secretary Minoru Kihara told reporters on Monday.
Tokyo lodged protests with China over Xue's remarks, while Beijing lodged its own with Japan over Takaichi's.
Xue's post has since been taken down - but the dust from the barbed exchanges hasn't settled yet.
On Tuesday, Takaichi declined to retract her remarks, which she defended as 'consistent with the government's traditional position'. She did note, however, that she would be careful about commenting on specific scenarios from now on.
Then on Thursday, China's foreign ministry posted in Japanese and English on its X account, warning Japan to 'stop playing with fire' and added that it would be an 'act of aggression' if Japan 'dares to meddle in the cross-Strait situation'.
Chinese Vice Foreign Minister Sun Weidong also summoned the Japanese ambassador to China that same day to express their unhappiness.
Sun called Takaichi's remarks 'extremely wrong and dangerous' and demanded that Japan withdraw the comments, according to state media Xinhua. He also warned that 'otherwise all consequences must be borne by Japan.'
Japan's ambassador explained that their position on Taiwan 'has not changed' and refuted Beijing's remarks, Chief Cabinet Secretary Minoru Kihara told reporters on Friday.
'It is the consistent position of the Japanese government that we hope for a peaceful resolution of issues surrounding Taiwan through dialogue,' he said during the daily news briefing.
A long history of animosity
There is longstanding animosity between the two countries, which can be traced back to a series of armed conflicts in the 1800s and Japan's brutal military campaign in China during World War Two.
This was referenced in a statement released by China's Ministry of Foreign Affairs on Thursday when it said that 'should Japan fail to draw lessons from history and dare to take reckless risks, even resorting to military intervention in the Taiwan Strait situation, it will inevitably suffer heavy losses and pay a bitter price in the face of the iron wall of the Chinese People's Liberation Army'.
Historical grievances have remained sore spots in bilateral relations ever since. But the recent ascension of Takaichi, a protégé of the late former prime minister Shinzo Abe, suggests more tensions may lie ahead.
The conservative leader is pursuing closer ties with the US and has pledged to increase Japan's defense spending - raising some alarm in Beijing.
