Security tightened as US Navy Ohio-class submarine arrives in Gibraltar Harbour

One of the largest nuclear-powered submarines operated by the US Navy has been sighted in Gibraltar.

Gibraltar Broadcasting Corporation (GBC) said the arrival of the USS Alaska – one of 18 Ohio-class nuclear submarines, armed with Trident II D5 ballistic missiles – prompted tighter security, including a 200-metre exclusion zone around the South Mole, in the southern section of Gibraltar Harbour.

The broadcaster also reported that a contingent of Royal Marines had arrived on the Rock aboard RAF transport aircraft.

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Boomers

As the cornerstone of the US Navy's nuclear deterrent force, the Ohio-class comprises 14 ballistic missile submarines and four guided submarines. 

Measuring roughly 171 metres in length and with a displacement close to 18,750 tonnes, they are among the largest submarines operated anywhere in the world. 

Nicknamed boomers – referring to the devastating sound their Trident missiles can create – they form the most survivable leg of the US nuclear triad.

As of yet, there has been no confirmation of the nature of USS Alaska's sighting. 

As a gateway to the Mediterranean, the strait is a frequent transit route for submarines, particularly those operated by Nato. 

However, with President Trump’s latest post on Truth Social, where he dismissed Iran's response to US proposals to end the war as "totally unacceptable", it could signal something larger as tensions in West Asia continue to escalate.