From DC's perspective this is all about China, it's about countering an ascending and increasingly hostile peer competitor in the US' main theater of operation - aka the Indo-Pacific. The current trajectory there is one of Washington's dominance and lead eroding leading to a potential US defeat. And if the US folds in the Indo-Pacific it will be the end of the USD and US Empire.
Despite their many miscalculations and mistakes the Chinese do play the long game and have been semi-competent at it. Beijing's greatest strength is its authoritian One Party State type of rule, its gigantic manufacturing base and it's large populace. It's greatest weaknesses are its geo-strategic location, resource poor status and ambiguously its One Party State type of rule again.
The balance of power in the Indo-Pacific is upending fast. The Changs' manufacturing base is of such an enormous size that their military build up is directly threatening DC's escalatory and military dominance in the Indo-Pacific. Chinese hardware ranges from low- to medium quality yet this is ultimately irrelevant as their production numbers are so gigantic that they can simply out-produce the US in any type of prolonged direct or indirect conventional conflict. Keep in mind that most if not all of China's civilian production sites are dual use as well meaning that in the case of hot conflict the Chinese will turn up their manufacturing numbers even beyond current already impressive numbers.
All of the Trump Administration's foreign policy and many of its economic policy decisions circle back towards this pivot towards the Indo Pacific/ China. The war in Ukraine was low key dialed down and off-loaded on DC's previously freeloading European allies. Venezuela was flipped due to its role in China's oil security. The Panaman Canal was secured due to Beijing's interference and its potential for blocking. Cuba is in the process of being flipped due to its potential as a escalation equalizer in the event of a US move. The Mexican Cartels are in part a Chinese proxy due to the CCP's role in the fentanyl trade and moneylaundering through Chinese banks, Islamabad got the greenlight to F up Afghanistan due to covert talks on a Iranian-Chinese pipeline through Afghan territory etc. Likewise the tariff wars, rare earth policies, reshoring, increases in military budgets and economic decoupling are meant to weaken China and make the US more resilient.
Iran fits the mould as well. Iran is a vital chain in China's long term strategy to create secure and stable sanction proof hydrocarbon lifelines towards the Chinese mainland. Iran is China's biggest import partner and that number is likely even underestimated due to shenanigans to evade sanctions. China's oil question is also why the BRI exists, and why the Chinese have all but in name abandoned their non-interference policy in Myanmar - the junta is in cahoots with Beijing and Persian Gulf oil is projected to be offloaded in Myanmar ports to be funneled towards the Yunnan through pipeline.
China needs Iran's oil. Beijing really couldn't care less about either the Islamic Republic or the Jewish state, any talk on that is red meat for buckos. It really is all about Iranian oil and keeping Washington away from that oil. Likewise Beijing needs to Strait of Hormuz to remain open - you see the Chang juxtaposition and bind already appearing right there. If the US flips Iran thereby taking over the country's oil market it would mean a serious setback to China's long term strategies, possibly delaying any move on Taiwan for years. Likewise it's why the Trump Administration is acting on Iran, there must have been a sense of urgency.