Iran carried out military drills with Russia on Thursday days after its unprecedented closure of the Strait of Hormuz in a fierce warning to US President Donald Trump, as tensions continued to escalate between the nations.
The announcement of the joint naval exercises in the Gulf of Oman came as the USS Gerald R. Ford, the world's largest aircraft carrier, arrived near the mouth of the Mediterranean Sea, joining other military assets the US has built up in the region.
The drills follow Tuesday's Revolutionary Guards' exercises in the Strait of Hormuz, the narrow opening of the Persian Gulf through which a fifth of the world's traded oil passes.
Tehran temporarily shut down parts of the vital waterway and fired cruise missiles, in a stark warning of the potential fallout to the world economy if the US goes through with its threats to attack Iran.
The military exercises ran parallel to diplomatic talks in Geneva, where Abbas Araghchi, the Iranian foreign minister, held a second round of indirect nuclear talks with Jared Kushner and Steve Witkoff on Tuesday.
JD Vance, the US Vice-President, subsequently warned that the theocratic regime was failing to acknowledge Trump's 'red lines', amid a heavy build up of American warplanes travelling to the Gulf.
The movements of additional American warships and airplanes don't guarantee a US strike on Iran - but it does give President Trump the ability to carry out one should he choose to do so.
Polish Prime Minister Donald Tusk urged all of Poland's citizens to evacuate Iran on Thursday, warning that the potential to leave might no longer be possible 'within a few hours'.
'Please leave Iran immediately ... and do not go to this country under any circumstances,' Tusk said.
Trump has so far held off on striking Iran after setting red lines over the killing of peaceful protesters and Tehran holding mass executions, while reengaging Tehran in nuclear talks earlier disrupted by the Iran-Israel war in June.
'Should Iran decide not to make a Deal, it may be necessary for the United States to use Diego Garcia, and the Airfield located in Fairford, in order to eradicate a potential attack by a highly unstable and dangerous Regime,' Trump wrote on his Truth Social platform, seeking to pressure the United Kingdom over its plans to settle the future of the Chagos Islands with Mauritius.
Meanwhile, Iran is struggling with unrest at home following its crackdown on protests, with mourners now holding ceremonies honoring their dead 40 days after their killing by security forces.
Some of the gatherings have included anti-government cries, despite threats from authorities.
The drill Thursday saw Iranian forces and Russian sailors conduct operations in the Gulf of Oman and the Indian Ocean.
It was aimed at 'upgrading operational coordination as well as exchange of military experiences,' Iran's state-run IRNA news agency claimed.
Rear-Adml Hassan Maghsoudlou, a spokesman for the drill, said Iran would be conducting 'anti-terrorism and vessel protection operations', with the goal of enhancing 'security and sustainable maritime interactions in the Gulf of Oman and northern Indian Ocean'.
China had joined the 'Security Belt' drill in previous years, but there was no acknowledgment it participated in this round.
In recent days, a vessel that appeared to be a Steregushchiy-class Russian corvette had been seen at a military port in the Iranian city of Bandar Abbas.
Iran also issued a rocket-fire warning to pilots in the region, suggesting they planned to launch anti-ship missiles in the exercise.
Meanwhile, tracking data showed the Ford off the coast of Morocco in the Atlantic Ocean midday Wednesday, meaning the carrier could transit through Gibraltar and potentially station in the eastern Mediterranean with its supporting guided-missile destroyers.
The £9.5billion floating fortress transports 90 aircraft - more than six RAF squadrons - and is equipped with some 4,000 sailors and airmen.
Having the carrier there could allow American forces to have extra aircraft and anti-missile power to potentially protect Israel and Jordan should a conflict break out with Iran.
The US similarly placed warships there during the Israel-Hamas war in the Gaza Strip to protect against Iranian fire.
The combination of the Ford strike group and the USS Abraham Lincoln aircraft carrier, already deployed in the Arabian Sea, has led analysts to predict that Trump is preparing a sustained military campaign against Tehran.
'He is spending a lot of time thinking about this,' a source told CNN, adding that the president has found himself arguing both in favour of and against the military action.
Trump has also spent recent days taking informal polls of his aides and military advisors over what to do, but it remains unclear when the president will make the final call.
Earlier on Wednesday, it was revealed the president is on the verge of greenlighting a 'massive, weeks-long' military campaign against Iran that would be seen as all out war.
Sources told Axios the campaign would have a broader regime-change objective against the Ayatollah, and the US and Israel would also launch the operation in a military joint effort.
As well as two aircraft carriers, a dozen warships, and hundreds of fighter jets equipped with advanced air defense systems,Trump's armada off the coast of Iran continues to swell.
More firepower is on the way as 150 military cargo flights have begun rapidly transferring weapon systems and ammunition to US Middle East bases.
Dozens of US fighter jets, including F-35s, F-22s and F-16s, left bases in the US and Europe in recent days to head to the Middle East, according to the Military Air Tracking Alliance (MATA), a team of about 30 open-source analysts that routinely analyses military and government flight activity.
The team says it has also tracked more than 85 fuel tankers and over 170 cargo planes heading into the region.
Steffan Watkins, a researcher based in Canada and a member of MATA, said he had spotted support and reconnaissance aircraft - including six of the military's early-warning E-3s - head to a base in Saudi Arabia.
Regional allies, including Turkey and Saudi Arabia, urged the White House to back off a strike over fears it could lead to a wider regional war with the Ayatollah.
On Tuesday, Khamenei directly threatened the US president when he said he would 'sink' US warships stationed in the Gulf.
'The strongest army in the world might sometimes receive such a slap that it cannot get back on its feet,' he said.
'Of course a warship is a dangerous apparatus, but more dangerous than the warship is the weapon that can sink the warship into the depths of the sea,' Khamenei added.
Mourning ceremonies for those killed by security forces in the protests last month also have increased.
Iranians traditionally mark the death of a loved one 40 days after the loss.
Both witnesses and social media videos showed memorials taking place at Tehran's massive Behesht-e Zahra cemetery.
Some memorials included people chanting against Iran's theocracy while singing nationalistic songs.
The demonstrations began December 28 at Tehran's historic Grand Bazaar, initially over the collapse of Iran's currency, the rial, then spread across the country.
Tensions exploded on January 8, with demonstrations called for by Iran's exiled crown prince, Reza Pahlavi.
Iran's government has offered only one death toll for the violence, with 3,117 people killed.
The US-based Human Rights Activists News Agency, which has been accurate in previous rounds of unrest in Iran, puts the death toll at over 7,000 killed, with many more feared dead.
The internet blackout, now showing signs of easing, has made it extremely difficult to document the full extent of the death toll, with Iranian medics suggesting the true number could exceed 30,000.