The United States and Iran are locked in an increasingly escalatory cycle of attacks that they each claim are aimed at preventing the other from securing military dominance over the Strait of Hormuz.

As the US pounds southern Iran and in recent days other parts of the country, Tehran too has hit back, striking military bases where US forces are deployed in neighbouring nations in the Gulf and Jordan.

Projectiles fired by both the US and Iran have also hit civilian infrastructure, raising questions over potential violations of international law, even as the fragile memorandum of understanding (MoU) that the two countries signed in June has collapsed.

“We’re going to knock out all their power plants. We’re going to knock out all their bridges unless they get to the table and negotiate,” US President Donald Trump threatened in a Fox News interview last week. He made similar threats against civilian infrastructure in April.

At least 50 people have died in Iran since the resumption of hostilities this month, and 500 have been wounded since July 15, according to Iranian authorities. Dozens of locations in southern and northwestern Iran have been hit in the past week, ranging from military command centres to railways and airports.

Iran’s Islamic Revolutionary Guard Corps (IRGC) has hit back by striking neighbouring Gulf countries where US military assets are based, resulting in the deaths of at least three US soldiers.

International humanitarian law explicitly forbids the targeting of civilian infrastructure during conflicts. The US and Israel hit several civilian sites in the first phase of the war that they launched against Iran on February 28, including a girls school in Minab, where at least 170 people were killed.

A spokesperson for United Nations Secretary-General Antonio Guterres said on Friday that he was “particularly concerned about attacks on civilian infrastructure in Iran and across the region”, adding that “such attacks are unacceptable”.

So what counts as civilian infrastructure, and what places have been hit so far in the second wave of the US-Israel war on Iran? Here’s what we know:

What does the law say?

The 1949 Geneva Conventions and their Additional Protocols of 1977 forbid attacks or reprisals on civilian infrastructure or “objects” during a conflict.

Civilian infrastructure includes “all objects which are not military objectives”, the law says, and which are “normally dedicated to civilian purposes, such as a place of worship, a house, or other dwelling or a school”.

These also include any facilities that support the day-to-day lives of civilians and are crucial to how a society functions: roads, bridges, railways, airports, electrical plants, sewage systems, hospitals, and phone and internet systems, for example.

The treaty states that drinking water installations and supplies, irrigation works, food, crops, livestock, dams, dikes and nuclear power generation plants also may not be targeted.

When in doubt about whether an object is serving a military or civilian purpose, parties must assume it is civilian and thus cannot attack it, the law states.

Can civilian infrastructure be targeted?

Yes, under specific and carefully determined circumstances.

Civilian infrastructure becomes a legitimate target only when it can be proven that it was “used for military purposes at the time of the attack and that its destruction provides a definite military advantage”, according to the treaty.

Even so, the law mandates that such attacks must remain “proportionate to the military advantage”.

In short, attacks on suspected civilian objects are prohibited if the risks to civilians – deaths, injury and the proper functioning of civilian life – outweigh their military gains.

“The basic presumption is that infrastructure is civilian and protected until such time it has become” clear that the enemy is using or has decided to use it for military purposes, Luke Moffett, law professor and civilian harm expert at Queen’s University Belfast, told Global News Insight.

The US and NATO forces used this justification for past attacks on electrical or water plants in Iraq or Libya although they caused civilian harm, the professor said.

But there’s a thin line between preventing the enemy from using civilian infrastructure and seriously harming civilians or how people live.

“The problem with the principle of proportionality is that it is difficult to calculate as you need to compare different values like civilian damage and military advantage,” Marco Roscini, professor of international law at Westminster Law School in London, said, adding that a ‘reasonable military commander’ must carry out the assessment.

Militaries, therefore, have to constantly verify that targets provide a military advantage and civilian harm is not excessive, Moffett said.

“Otherwise, it can be an indiscriminate attack,” he said.

Such indiscriminate attacks can be prosecuted as war crimes.

Where has the US hit Iran?

Iranian media and officials have reported several US attacks on civilian infrastructure as defined by the Geneva Conventions, particularly in southern coastal areas close to the Strait of Hormuz. Washington said it has exclusively targeted military sites, “including military logistics infrastructure”.

Analysts said lawyers in the US military may be clearing some targets as “dual use”, meaning they might potentially be used for military purposes.

Road and bridge networks

• In the city of Bandar Abbas, where Iran’s main naval hub and largest commercial port are located, a railway facility and the Kahurestan Bridge were hit. The bridge links the port on the Strait of Hormuz to other cities. Multiple fatalities occurred during the attacks, and one vehicle fell off the bridge.
• In another part of Hormozgan province, six bridges were destroyed in Bandar Khamir county, hampering traffic to and from Bandar Abbas, the provincial capital. They include the Gariyeh Bridge, a bridge near Latidan village; two smaller bridges on the Kahurestan-Lar road; the Marou village bridge linking Bandar Khamir with Bandar Abbas; and an uncompleted bridge along the Bandar Khamir-Keshar-Bandar Abbas axis.
• The Aq Taqeh Khan railway bridge in Golestan province, which links Iran with China and Russia through Turkmenistan and Kazakhstan, was also hit.
• Attacks hit railway networks between Tehran and the northeastern city of Mashhad during the burial of Supreme Leader Ali Khamenei.

Health facilities

• The Shahid Baghaei Hospital in Ahvaz in western Iran was hit and rendered inoperable, causing more than 200 patients to be evacuated.

Water and food facilities

• In Musiyan in southwestern Iran, a bottled water facility was hit. The area was previously targeted in the first phase of the war.
• The desalination plant in Bonji village was hit in Jask county in Hormozgan province, cutting off water supplies to 10,000 people.

• Wheat storage facilities were reportedly hit in Hoveyzeh county and another in Dasht-e Azadegan county, both in Khuzestan province, which sits on the border with Iraq.
• A water desalination plant was also hit in Bomani, Sirik county, Hormozgan province, during low-scale skirmishes after the April ceasefire and just before the MoU was signed.

Airports and seaports

• Iranian officials reported an attack on the airport in the southern city of Iranshahr that injured one person, damaged electrical facilities and a fuel tank, and triggered a power outage.
• In Semnan, the capital of Semnan province in northern Iran, parts of the airport were hit and suffered minor damage.
• Iranian media also reported attacks on Tohid-Jam airport in Jam in the south.
• Fishing and commercial piers were hit in Sirik county on the Strait of Hormuz, causing multiple casualties.
• Fishing and commercial piers were also hit in Bandar Abbas.
• The Kish commercial harbour was hit in Hormozgan province.
• A fishing pier was hit in Asaluyeh county, Bushehr province, on the Gulf, causing fishermen’s boats to catch fire.

Communication towers

• One communication tower was hit in Bandar Abbas when the Communications Regulatory Authority was targeted.
• On Qeshm Island in the Strait of Hormuz, a communications tower was hit and damaged.

Residential areas, sewage systems and administrative buildings

• Attacks were reported in residential areas of Bandar Abbas.
• An environmental protection station was hit in Hajiabad, Hormozgan province, according to Iranian media.
• A search and rescue station was hit in Kish, Hormozgan province.
• A wastewater treatment plant in Bandar Abbas’s popular tourist site, the Bird Garden, was hit.

Nuclear power plants

• Strikes extensively damaged the Bushehr nuclear plant, Iran’s only operating nuclear plant, according to an Global News Insight investigation. Authorities said it’s still functional.
• The partly built Darkhovin nuclear facility in southern Khuzestan province was hit over the weekend.

What has Iran hit?

Iran has repeatedly targeted military bases – and increasingly, civilian infrastructure – in Kuwait, Oman, Jordan and Qatar. The IRGC has insisted it is targeting US military assets.

• Kuwait: Officials said Iranian attacks have hit a power and water desalination plant repeatedly, resulting in large fires and destabilising the main electrical grid. An oil facility was also hit.
• Qatar: Officials said a child was injured from falling debris in Doha after interceptors were used to ward off Iranian missiles. It’s unclear whether civilian infrastructure or residential areas were explicitly targeted.
• Strait of Hormuz: Several commercial tankers and vessels have been hit in the Strait of Hormuz off Oman for using routes Iran did not authorise.