A legal battle between Iran and the United States over renewed sanctions imposed on Tehran opened Monday, with Tehran's lawyers arguing that the measures are hurting Iran's economy. 

The hearings started at the International Court of Justice (ICJ) in The Hague on Monday afternoon and are scheduled to run for four days.

Here are four key questions regarding the case:

What is the case about?

Iran's attempt to block the reinstatement of sanctions is the latest in a series of court battles that Tehran and Washington are fighting at the ICJ.

US President Donald Trump announced on May 8 that he was pulling out of a landmark deal between Iran and major powers aimed at preventing Tehran from acquiring a nuclear weapon. The deal agreed with the UN's five permanent Security Council members and Germany in 2015 limits Tehran's stockpile of enriched uranium until 2031 in exchange for sanctions relief. 

Read more: 

Iran nuclear deal: What now?

International reaction: US withdrawal from Iran nuclear deal

Blasting the accord as a "horrible, one-sided deal", Trump re-imposed a wave of tough, unilateral sanctions. Tehran now accuses Washington of "besieging" its economy and wants the Hague-based court – which rules in disputes between countries – to order the US to temporarily halt punitive measures, while the judges mull the deeper merits of the case. 

What is Iran's position?

Iran's representative Mohsen Mohebi branded the sanctions "naked economic aggression".

His team of lawyers told the court in The Hague the measures were already devastating Iran's economy and threatening the welfare of its citizens.

"The United States is publicly propagating a policy intended to damage as severely as possible Iran's economy and Iranian nationals and companies," Mohebi said. "Iran will put up the strongest resistance to the US economic strangulation, by all peaceful means."

The sanctions are targeting financial transactions and imports of raw materials, cars and aircraft among other things.

The second wave of punitive measures is due to hit Iran in early November, targeting its vital energy sector including oil exports.

Iran's lawyers said the sanctions would cause it "irreparable prejudice", and urged the court to order the suspension of the sanctions pending a definitive ruling.

What will be Washington's argument?

US lawyers are due to give their response in arguments before the court on Tuesday, with experts expecting them to challenge the ICJ's jurisdiction.

"We will vigorously defend against Iran's meritless claims this week in The Hague," said Pompeo.

He said Iran's lawsuit was "an attempt to interfere with the sovereign rights of the United States to take lawful actions, including re-imposition of sanctions, which are necessary to protect our national security".

What to expect at the ICJ?

The ICJ is expected to take a couple of months to decide whether to grant Tehran's request for a provisional ruling. A final decision could take years.

While the ICJ judgments are binding, final and without appeal, it remained unclear whether any decision will be implemented, with both Iran and the US in the past ignoring ICJ rulings against them.

The case is the second brought by Tehran against Washington since 2016. That year it brought a suit at the ICJ against the freezing of around 2 billion US dollars of Iranian assets abroad which US courts say should go to American victims of terror attacks. Hearings, in that case, are due to start on October 8.

In both cases, Iran is basing its claim on the obscure 1955 Treaty of Amity and Economic Relations, signed long before the country's Islamic revolution. Despite the treaty, the two countries have not had diplomatic ties since 1980.