Iran has warned it has prepared “new cards” to use on the battlefield as fears grow that a two-week ceasefire with the US may end without a peace agreement.

Mohammad-Bagher Ghalibaf, Tehran’s parliamentary speaker and top negotiator, said Trump wants to “justify renewed warmongering” by “imposing a siege and violating the ceasefire”.

"We do not accept negotiations under the shadow of threats, and in the past two weeks, we have prepared to reveal new cards on the battlefield," he added in a post on X.

The US says it has depleted Iran’s missile stores and launch capabilities. But before the ceasefire, Iran’s Revolutionary Guards had been able to fire a steady stream of missiles and drones at targets across the Gulf.

Exactly what new cards Tehran has under its sleeve are unclear - we take a look at some possibilities.

Close the Bab-El-Mandeb Strait using the Houthis

The Houthis, the Iran-aligned Yemeni rebel group who control significant portions of the country’s west, have already threatened that the strategic El Mandab Strait could be shut if Trump does not change course.

"If Sana’a makes the decision to close the Bab al-Mandeb, no force would be able to reopen it," he said.

“It is best for Trump—and the complicit world—to immediately end all practices and policies that obstruct peace, and to show the respect required for the rights of our people and nation.”

The Bab-El-Mandeb Strait is a vital shipping corridor connecting the Red Sea to the Gulf of Aden and the Indian Ocean, through which a large portion of global trade, including energy supplies, flows.

In 2017, around nine per cent of total seaborne-traded petroleum, including crude oil and refined petroleum products, flowed through the Strait, according to the US Energy Information Administration.

Since Israel’s invasion and bombardment in Gaza began after the Hamas-led October 7 attacks, the Houthis launched several attacks on Israel, US and British tankers and commercial ships.

But a complete closure of the Strait would be new territory for tankers passing through the waterway - and it is unclear how effectively the Houthis would be able to carry it out.

Cyber attacks

Security agencies have now warned of the threat of cyber attacks by Iran-affiliated proxies, especially around water and energy facilities.

“Cyberattacks on drinking water and wastewater systems directly threaten public health and community resilience,” Jeffrey Hall, an administrator at the Environmental Protection Agency (EPA), said in a statement.

“A single breach can disrupt treatment or introduce contaminants, damage equipment, and erode public trust.”

The FBI, National Security Agency, US Cyber Command, US Department of Energy, and the Cybersecurity and Infrastructure Security Agency, all supported the advisory.

Iran has previously been accused of carrying out cyber attacks, including a large power outage in Turkey in 2015.

Tehran was also accused of several possible breaches of Israeli government websites in 2022, and in 2023, the US alleged an Iran-affiliated group had compromised at least 75 devices in several sectors.

Iran says the US and Israel has carried out several cyber attacks against it.

Political attacks

Tehran could look towards political targets to avenge the assassinations of former supreme leader Ali Khamenei and several of the regime and military’s top brass by the US and Israel.

Iran could seek to target diplomatic, consular or trade missions belonging to the US and its allies.

It may also look at carrying out assassinations of key individuals linked with the US and its allies.

New attacks on energy sites and infrastructure in the Gulf

Iran could resume its attacks on energy sites and infrastructure across the Gulf, which have already caused significant economic damage.

According to the Atlantic Council, around 83 per cent of Iran’s total missile and drone strikes during the war targeted Gulf Cooperation Council (GCC) countries, in particular the United Arab Emirates (UAE).

Iranian attacks have already damaged as much as $58 billion (£43bn) worth of energy infrastructure, according to an estimate published by consulting firm Rystad Energy on Wednesday, according to US business news site CNBC.

Iran has targeted the oil and gas infrastructure of its Gulf Arab neighbours, such as production facilities, refineries, and pipelines, among other targets. Israel has attacked natural gas and petrochemical facilities in Iran.

Fatih Birol, executive director of the International Energy Agency, said more than 80 energy facilities have been attacked in total since US-Israeli strikes sparked the war on 28 February, with more than a third of those severely damaged.