United States President Donald Trump has threatened to unleash “Hell” on Iran by demolishing its critical infrastructure, including its bridges and power plants, if it does not open the Strait of Hormuz by early on Wednesday in Tehran.

Trump casually described his plans, which many experts said would amount to war crimes, as “Bridge Day” at a time when the US and Israel have already bombed multiple Iranian universities, hospitals, schools, research centres and pharmaceutical companies.

Just last week, a US double-tap strike obliterated the newly constructed B1 bridge in Karaj, a city west of Tehran, killing eight civilians who were picnicking under it as Iran celebrated Nowruz, the Persian New Year. The B1 was an unfinished project, yet it was targeted as part of what analysts called a strategy to “de-develop” the nation.

Now as another of Trump’s deadlines over the Strait of Hormuz approaches, international observers are sounding the alarm over the implications if the US president were to indeed order the bombing of Iran’s bridges.

According to Iran’s Bridge Management System (BMS), the country has roughly 300,000 bridges and technical structures. Only about 185 bridges exceed 100m (330ft) in length, and a mere 42 bridges have a main span – the longest unsupported distance between two consecutive pillars – of more than 50m (165ft).

Based on their scale and economic importance, here are five of Iran’s most prominent bridges:

Persian Gulf Bridge (Qeshm Island)

• Location: Hormuzgan province
• Dimensions: 3.4km (2.1 miles) long
• Status: unfinished (15 to 18 percent physical progress)
• Background: The Persian Gulf Bridge was a “dream project” for more than 50 years, and ground was broken in 2011. While the bridge remains unfinished due to funding hurdles, its massive underwater foundations and caissons are in place. Once completed, it will connect Qeshm Island – the largest of Iran’s islands in the Gulf, believed to be home to an underground missile arsenal – to Bandar Abbas, Iran’s biggest mainland port.
• What is at risk: Even in its current state, the bridge represents an investment of up to $700m and is the centrepiece of the International North-South Transport Corridor, which also includes India and Russia. Targeting its massive concrete foundations would erase decades of national planning and directly strike at Chinese-backed credit lines, in effect killing Iran’s hopes of a direct link to the island from the mainland.