A US military surveillance drone has been shot down by Iranian forces while flying over the Strait of Hormuz.
Iran’s Islamic Revolution Guards Corps (IRGC) said the drone had violated Iranian airspace. But US military said it had been over international waters.
IRGC commander-in-chief Maj-Gen Hossein Salami said the downing of the drone sent a “clear message to America” that Iran’s borders were its “red line”.
It comes at a time of escalating tension between the US and Iran.
On Monday, the US defence department said it was deploying 1,000 extra troops to the region in response to “hostile behaviour” by Iranian forces.
The US has also accused Iran of attacking two oil tankers with mines last Thursday just outside the Strait of Hormuz, in the Gulf of Oman. Iran rejects the allegation.
It was the second time in a month tankers have been attacked close in the region, through which a fifth of the world’s oil passes each day.
Tensions were further fuelled on Monday when Iran announced its stockpile of low-enriched uranium would next week exceed limits it agreed with world powers under a landmark nuclear deal in 2015.
Iran stepped up its production in response to tightening economic sanctions from the US, which unilaterally withdrew from the deal last year.
What happened on Thursday?
The IRGC said its air force shot down the US drone in the early hours of Thursday after the unmanned aircraft violated Iranian airspace near Kuhmobarak in the southern province of Hormozgan.
The drone was identified by the IRGC as a RQ-4 Global Hawk, but the US military official told Reuters news agency the drone was a US Navy MQ-4C Triton, a maritime patrol and reconnaissance aircraft based on the RQ-4B Global Hawk.
Later, in a speech carried live on Iranian state TV, Gen Salami warned the US that it needed to respect Iran’s territorial integrity and national security.
“The downing of the American drone was a clear message to America… our borders are our red line and we will react strongly against any aggression.”
He added: “Iran is not seeking war with any country, but we are fully prepared to defend Iran.”
First direct incident of crisis
This is the first direct incident of the current crisis involving the US and Iranian militaries and is a powerful reminder of the dangers of escalation in the Gulf.
As far as the Iranians are concerned, the downing of the drone was intended to send a clear and explicit message to the Americans – “our borders are our red line” – a point underscored by the IRGC’s commander-in-chief.
So there is no doubting who shot down the US drone, an MQ-4C Triton. It is a massive aircraft with a wing-span equivalent to a small airliner. But the two sides differ as to where it happened. The Iranians say it was in their airspace; the Americans say that it was not.
According to some reports, US President Donald Trump himself is eager to dial down the tension, fearing a spill-over into outright conflict. But this is just the kind of incident that could provoke just such a cycle of action and response.
Is this the first time Iran has targeted a US drone?
Last week, the US military accused Iran of attempting to shoot down a US MQ-9 Reaper armed drone with a surface-to-air missile in an attempt to disrupt surveillance of one of the tankers that was attacked, the Kokuka Courageous.
The drone had earlier observed a fire on board the other tanker, the Front Altair.
The previous week, another US MQ-9 Reaper was shot down over Yemen by a surface-to-air missile fired by the Iran-backed rebel Houthi movement.
The US military said the altitude of the engagement “indicated an improvement over previous Houthi capability, which we assess was enabled by Iranian assistance”. Iran denies providing weapons to the Houthis.
In 2011, Iran said it had captured a US RQ-170 Sentinel reconnaissance drone that had been reported lost by US forces in neighbouring Afghanistan. It developed its own version of the drone, one of which was shot down by Israel last year.