At least 30 US military planes have been moved from bases in America to Europe over the past three days, flight tracking data reviewed by BBC Verify has shown.

The planes in question are all US military tanker aircraft used to re-fuel fighter jets and bombers. According to Flightradar24, at least seven of these – all KC-135s – stopped off in US airbases in Spain, Scotland and England.

The flights come as Israel and Iran continue to exchange strikes, after Israel launched an operation on Friday that it said was to destroy Tehran’s nuclear programme.

It is unclear whether the US movements are directly connected to the conflict, but one expert told BBC Verify that the tanker aircraft flights were “highly unusual”.

Justin Bronk, a senior analyst with the Royal United Services Institute (Rusi) think tank, said that the deployments were “highly suggestive” that the US was putting in place contingency plans to “support intensive combat operations” in the region in the coming weeks.

The seven jets tracked by BBC Verify have since travelled on and according to flight tracking data could be seen flying east of Sicily as of Tuesday afternoon. Six had no stated destination – one landed on the Greek island of Crete.

But the former head of Irish Defence Forces, Vice-Admiral Mark Mellett, said that the movements could be part of a broader policy of “strategic ambiguity” that could be attempting to influence Iran to make concessions in talks over its nuclear programme.

Israel initially launched an attack on Iranian nuclear infrastructure on Friday, just a day after President Donald Trump’s deadline to Iran to strike a deal on suspending its nuclear programme expired.

The jet movements come amid reports that the US has also moved an aircraft carrier – the USS Nimitz, from the South China Sea towards the Middle East. The Reuters news agency reported that a planned event involving the ship in Vietnam was cancelled after what the US embassy in Hanoi called an “emergent operational requirement”.

MarineTraffic, a ship-tracking website, showed that the USS Nimitz’s last location was in the Malacca Strait heading towards Singapore early on Tuesday. The Nimitz carries a contingent of fighter jets and is escorted by several guided missile destroyers.

The US has also moved F-16, F-22 and F-35 fighter jets to bases in the Middle East, three defence officials told Reuters on Tuesday. The tanker planes moved to Europe over the past several days can be used to re-fuel these jets.

Earlier on Tuesday, Vice-President JD Vance suggested that the US could intervene to support Israel’s campaign, writing on social media that Trump “may decide he needs to take further action” to end Iran’s nuclear programme.

Tehran is believed to run two principal underground enrichment sites. Natanz has already been hit by Israel, and Fordo is buried deep within a mountain complex near the city of Qom.

To penetrate the facility, the US would likely have to use GBU-57A/B Massive Ordnance Penetrator (MOP) munitions, two senior Western military officers told BBC Verify. MOPs are huge, 30,000lb (13,600kg) bombs also known as “bunker busters”.

The bomb is the only conventional weapon of its kind that is thought to be capable of breaching up to 200ft (60m) of concrete. Only the B-2 stealth bomber can carry the munitions.

Recently, the US has had a squadron of B-2 bombers at its base on the island of Diego Garcia. While the island is some 2,400 miles from Iran’s southern coastline, their location on Diego Garcia would put them well within striking range of Iran.

“You would be able to maintain a sustained operation from [Diego Garcia] far more efficiently,” Air Marshall Greg Bagwell – a former RAF deputy operations chief – told BBC Verify. “You could literally have them round the clock operating.”

Satellite images first showed B-2 bombers had been stationed on Diego Garcia at the end of March, but the most recent imagery from the island no longer shows the bombers present.

Vice-Admiral Mellet said he would expect to see the bombers on the island ahead of any operation targeting Iran and called their absence “a missing piece of the jigsaw”.

Air Marshall Bagwell agreed. But he noted that B-2s have been known to operate for 24 hours at a time and could launch from the continental US if the White House decided to launch a strike.

“They’ve taken away any means for Iran to now defend itself, which obviously leaves any military or even the nuclear targets pretty much at the mercy of whatever Israel wants to do to it.”

Additional reporting by Merlyn Thomas.