Warships from the Nato Response Force (NRF) fleet are participating in the maritime module of Exercise Noble Justification in the Mediterranean Sea and Atlantic Ocean.
The exercise runs through to 26 October and is aimed at bolstering the response readiness to a range of Nato operational contingencies.
It also focuses on developing force integration and multinational interoperability, as well as joint capability via a high-density, high-risk scenario.
Nato Maritime Commander, UK Navy vice-admiral Peter Hudson said: "The exercise Noble Justification is a substantial opportunity for Nato to develop force integration, multinational interoperability and enhance readiness.
"It exercises a high-density, high-threat scenario in which Nato responds to a threat to its integrity and the sovereignty of its member states."
Warships will also take part in challenging training evolutions, which will boost their short-notice response capabilities to crisis situations worldwide.
The initial phase involves interoperability training in asymmetric multi-threat and maritime warfare operations, followed by the second phase, where forces will respond to a complicated crisis response scenario.
In addition to 5,000 military and naval personnel from 14 Nato nations, 23 warships from 16 Nato nations and a wide range of aircraft are taking part, including US B-52 Stratofortress bombers.
Participating nations include Belgium, Canada, Finland, France, Germany, Greece, Italy, the Netherlands, Norway, Poland, Portugal, Spain, Sweden, and Turkey, as well as the UK, and the US.
Image: The exercise is aimed at preparing and testing the highest readiness levels for rapid responses to any Nato contingency. Photo: courtesy of HQ AIRCOM Public Affairs Office.