US build-up of warships and fighter jets tracked near Iran
BBCBBC Verify has confirmed the location of US aircraft carrier the USS Abraham Lincoln near Iran using satellite imagery, as Washington continues to put pressure on the country over its military program and recent deadly crackdown on protesters.
US and Iranian officials are set to meet in Swizerland on Tuesday for a second round of talks. Iran says the meeting will focus on its nuclear programme and the potential lifting of economic sanctions imposed by the US. Washington has previously indicated it wants to discuss other issues as well.
The Abraham Lincoln, which leads a strike group with three guided missile destroyers, carries 90 aircraft including F35 fighters, and 5,680 crew, was reportedly deployed to the Gulf region in late January but has not been seen in satellite imagery until now. It has been located off the coast of Oman, around 700km from Iran.
The US has also reportedly sent the USS Gerald R Ford, the world's largest warship, to the Middle East, which could arrive in the region within the next three weeks.
The Abraham Lincoln's arrival adds to what we know about the current US military build-up in the Middle East over the past few weeks, where BBC Verify has tracked an increase of US destroyers, combat ships and fighter jets in the region.
ReutersWhat military assets has the US moved into the Middle East?
Publicly available images from the European Sentinel-2 satellites show Abraham Lincoln in the Arabian Sea around 150 miles (240km) off the coast of Oman.
It had not been seen since it reportedly entered the region in January but it had been crossing the open sea where satellite coverage is limited. Military assets on land are more visible and frequently captured on satellite.
It means we have now tracked 12 US ships in the Middle East through satellite imagery: the Abraham Lincoln, a nuclear-powered Nimitz-class carrier, which together with three Arleigh Burke class destroyers forms a carrier strike group; plus two destroyers capable of carrying out long-range missile strikes and three specialist ships for combat near to the shore that are currently positioned at Bahrain naval station in the Gulf. Two other destroyers have been seen in the eastern Mediterranean near the Souda Bay US base, and one more in the Red Sea.
We have also been following the movements of US aircraft in the region, where we have seen an increase of F-15 and EA-18 fighter jets stationed in Muwaffaq Salti military base in Jordan, and an increase in US cargo planes and refuelling and communications aircraft moving towards the Middle East from the US and Europe.

How has Iran responded?
The US Central Command released images of the Abraham Lincoln flanked by destroyers, fighter jets, surveillance aircraft and coastguard vessels in the Arabian Sea in an apparent show of military prowess on 6 February, which Iran has met with its own show of force.
On Monday the Islamic Revolutionary Guard Corps (IRGC) launched a maritime drill in the Strait of Hormuz, located in the Gulf between Oman and Iran. The drill saw IRGC Commander‑in‑Chief Maj Gen Mohammad Pakpour inspecting naval vessels at a harbour before missiles are seen launching from a ship, the IRCG-linked Tasnim News Agency reported.
The Strait is considered one of the world's most important shipping routes and a vital oil transit choke point. Around a fifth of the world's oil and gas flows through the Strait, including from Kharg Island, Iran's main oil export terminal. Pakpour was seen flying over the island in a helicopter in the report showing Iran's latest military manoeuvres.

How does it compare with Venezuela and Operation Midnight Hammer?
Military intelligence expert Justin Crump told BBC Verify that the current US military preparations in the Middle East show "more depth and sustainability" than its manoeuvres ahead of the seizure of former Venezuelan president Nicholas Maduro in January, or the operation carrying out air strikes on Iran's nuclear facilities last June.
They all feature a carrier strike group and several destroyers operating independently. However, the US deployed its assets in Venezuela and Iran last year under quite different circumstances.
The US deployed the Gerald R Ford to the Caribbean ahead of its strikes on Venezuela, one of eight warships we tracked in the region at the time, though it used fewer aircraft as it could easily send jets from surrounding US bases on America's mainland or from its base in Puerto Rico instead. The US also deployed amphibious assault ships within the Caribbean, which can be used as launch platforms for helicopter operations as was seen with the capture of Maduro. But Venezuela's military is generally seen as less capable of defending itself or retaliating against the US.
When the US struck Iran last year in Operation Midnight Hammer, which targeted Iran's nuclear facilities, it was attacking a country with a much more powerful military than Venezuela. Iran's military is capable of hitting US bases across the Middle East.

During Midnight Hammer the US had two aircraft carrier strike groups in the region, five destroyers placed in the Mediterranean and Red Seas, and three combat ships in the Gulf. It had also moved squadrons of fighter jets and refuelling aircraft from the US to Europe, but the B2 stealth bomber flights that were used to hit the Fordo, Isfahan and Natanz nuclear sites actually took off from US bases in Missouri.
Crump, chief executive of risk and intelligence company Sibylline, said the build-up of US warships and aircraft, as well as eight existing airbases in the region would allow it to conduct a "fairly intensive and sustained strike rate" of about 800 sorties a day, with the aim of rendering any Iranian responses "ineffective".
"What we are seeing isn't just strike preparation, but rather a broader deterrent deployment capable of being scaled up or down," he said. "This means it has more depth and sustainability than the force packages arranged for either Venezuela or Midnight Hammer last year. It's designed to sustain an engagement and counter all potential responses against US assets in the region and, of course, Israel."
Additional reporting by Barbara Metzler, Ghoncheh Habibiazad, Thomas Copeland, Yi Ma
