The six-month-old war has been marked by a cycle of pauses followed by periodic flare-ups, with the US last reporting attacks on Iranian targets on Saturday, when US forces struck three Iranian oil tankers. Iranian state media reported on Sunday that Iran fired the Qassem Basir missile.
Despite US attempts to open up the Strait of Hormuz, Iran has continued to disrupt shipping through the critical artery for global oil and gas supplies, and there is no sign of progress towards a diplomatic breakthrough that could end the war which began with US and Israeli strikes on February 28.
The Islamic Republic has vowed to announce a new restricted zone in the Gulf in the coming days, along with maps of a new shipping corridor through the Strait of Hormuz.
The new restricted zone would begin from where the US blockade of Iran begins and extend into areas of the Gulf, Mohsen Rezaei, the secretary of Iran's Supreme National Security Council, told state television on Sunday, adding that any vessel entering the area would be placed on an Iranian sanctions list.
On Tuesday, Rezaei reissued dual economic and military threats on X.
"In recent days, Washington has received a clear warning from Iran's new missiles. Economic warfare will be met by a maritime exclusion zone across the Persian Gulf to the blockade perimeter. The operational posture toward US warships and bases has been fundamentally recalibrated," Rezaei said.
Rezaei was likely referring to the Qassem Basir ballistic missile that Iranian media reported was fired at US warships near the Strait of Hormuz. The US military said its warships evaded any missile attacks.
Despite major US barrages that have degraded Iran's conventional forces and punished its already ailing economy, it has maintained missile and drone capabilities to threaten oil tankers transiting the Strait of Hormuz without its permission and attack Gulf neighbours that are home to US military bases.
Iran has touted the Qassem Basir as an upgraded missile with improved manoeuvrability that can evade missile defence systems, with a guidance system that is effective against electronic warfare. The Fars news agency reported its first combat use came in June 2025 against Israel.
Some analysts conjecture Iran's leverage of the Strait of Hormuz may be dwindling while harsh new US economic sanctions are becoming increasingly difficult for Iran to withstand.
About one-fifth of global oil and liquefied natural gas shipments passed through the strait before the war, which enabled Iran to threaten tankers from Gulf neighbours seeking to export oil and gas, pressuring energy prices at a time when the war, which opinion polls show is unpopular in the US, has increased the risks for President Donald Trump's Republican Party in November congressional elections.
"Oil prices will drop precipitously, like everything else is dropping (but more!), when we WIN the war with Iran. Three Dollars a gallon, but ultimately, below Two Dollars a gallon. It will all happen quickly, and Iran will never have a Nuclear Weapon," Trump said on social media.
Trump has yet to achieve the aims he set out when he launched "Operation Epic Fury" in February: to end Iran's nuclear program, halt its ability to attack its neighbours and create conditions for Iranians to topple their leadership.
Tehran's clerical rulers remain in power and aim to emerge from the war stronger than before. They continue to demand sanctions relief and hope eventually to collect fees from ships using the strait.
Shipping data showed an average of just 10 commodity vessels per day transited the strait over the past 10 days, the lowest level since May.
