The Bulletin revealed yesterday that U.S. military aircraft were active in Mallorca airspace over the festive period overflying the island on their way to and from the U.S. base in Rota near Cadiz on the mainland - could they be monitoring Russian naval movements? The number of Russian ships transiting the Strait of Gibraltar and sailing into the Mediterranean and quite possibly Balearic waters during 2025 saw a significant increase of 50% compared to the previous year, EuropaSur reported.
Naval observer Michael J. Sánchez has documented that 299 ships passed through this strategic passage, including 43 warships, the highest number since 2021. Sánchez monitors the Strait from land and through public AIS (Automatic Identification System) systems. This allows him to identify and track ships that automatically transmit information such as the position, speed, course and identity of the vessels.
It works using VHF radio signals and is used by maritime authorities, ports and other vessels to improve navigation safety and prevent collisions. AIS is mandatory for most merchant and military vessels, although it can be voluntarily deactivated, which is common in certain sensitive transits, making it difficult to fully track maritime traffic. In this count, the observer recorded the movement of 155 vessels towards the Atlantic and another 144 towards the Mediterranean. By type of vessel, 137 were cargo ships, 107 were oil tankers, 43 were warships, 10 were tugs and two were fishing vessels.
The number of warships recorded is the highest since 2021, when the observer documented 47, and includes destroyers, frigates, corvettes and other combat vessels, despite the loss of Russia’s only base in the Mediterranean, Tartus in Syria, in early 2025. This count does not include Russia’s so-called ‘ghost fleet’, a group of ships, mainly tankers and merchant vessels, which operate to transport Russian crude oil and energy products outside international sanctions.
These ships often sail under flags of convenience, with opaque owners and insurers, frequently change their names and flags, and in many cases deactivate their AIS systems to avoid tracking. Due to these practices, the movements of this fleet are difficult to track and are not always reflected in official counts or visual observations.
The Spanish Navy has stepped up its surveillance of Russian vessels in the Strait of Gibraltar, the Alboran Sea and the western Mediterranean, in coordination with NATO allies and neighbouring countries such as France and Portugal. The maritime observer has also recorded an increase in activity in the last days of 2025 and the start of 2026. Between 30 December and 3 January, at least seven Russian-flagged vessels crossed the Strait, four of which were subject to international sanctions from the United States, the EU and the United Kingdom, reigniting the debate on the surveillance of this key maritime corridor crossed each year by more than 100,000 vessels of all types.
For example, two years ago, the Spanish offshore patrol vessel Centinela intercepted and monitored two Russian vessels, the frigate Admiral Kasatonov and the tanker Akademik Pashin, which are sailing in the western Mediterranean. At one point the Russian vessels were suspected of having entered Balearic waters but exact information was kept classified.