The film has released a poster in Chinese, swapping the English tagline "time runs out" for a clarion call to return to cinemas that roughly translates to "make every second count; invade the theatres".

Chinese cinemas reopened in regions at low risk for COVID-19 on July 20, taking in $12.6 million in their opening weekend. Currently, around 44 per cent of its cinemas are back in business, but have been required to operate at just 30 per cent capacity to allow for social distancing, as well as reduce their total number of screenings to half their usual tally.

Additionally, guidelines for reopening released by the National Film Bureau request that cinemas not screen films that are over two hours long - which could potentially pose problems for Tenet, which runs at two hours and 31 minutes.

This directive was soon contradicted, however, by Chinese authorities' subsequent approval of numerous films longer than two hours for nationwide theatrical release. Until the guideline is more formally lifted, it appears that cinemas in different regions under different levels of COVID-19 threat have been given varied amounts of leeway, or at least have been variously willing to stick their neck out and program longer films.

All eight of the Harry Potter films run over two hours, but they are all currently screening as part of the Shanghai International Film Festival. Yet at least two cinemas in Beijing said Wednesday in private chats posted to social media that due to the confusion, they currently didn't dare program approved, available titles over 120 minutes long - even the patriotic blockbuster Wolf Warrior 2, which runs to 123 minutes.

Elsewhere in China, however, that film's re-run has already made $1.1 million since cinemas reopened Monday.

Tenet had to reschedule its release numerous times due to COVID-19 before Warner Brothers this week settled on the unconventional plan of debuting it internationally before it hits North America. It's now prepared to open in around 70 countries abroad starting on August 26, including the UK, Australia, Canada, France, Germany, Italy, Japan, Korea and Russia. It will then premiere in select US cities over Labor Day weekend from September 3.

China is far and away the most important foreign market for Tenet director Christopher Nolan's films. The Chinese box office for almost every film he's made as either director or executive producer has blown away earnings from other territories by a large margin. The only exceptions are Dunkirk and The Dark Knight Rises, for which China was the second largest market globally behind the UK, and Batman Begins, which hit the Middle Kingdom all the way back in 2005, when its box office was still comparatively nascent.