The announcement of signing the Trinity House defense treaty between Berlin and London, repeatedly mentions Ukraine and the "new offensive capability" Kyiv will receive thanks to this cooperation.
Among the specific examples, the communique lists the commitment to arm the Sea King helicopters, which Germany is transferring to Ukraine, with "modern missile systems." The details are not disclosed but the number of known options is actually limited. Most of them revolve around developments by MDBA — unsurprising considering both Germany and Great Britain have jointly owned shares in this company.
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The range of helicopter-borne weapons offered by this pan-European manufacturer includes Brimstone missiles, the first and most likely candidate. This missile in baseline version is already well known to Ukrainian Armed Forces thanks to UK supplies, and there is a special Future Attack Helicopter Weapon (FAHW) variant for helicopters.
The problem, however, is that the FAHW was designed specially for AH-64E Apache Guardian helicopters of the British Army. Ultimately, London opted for the American AGM-179 JAGM instead. As for the manufacturer, it is unknown whether the project received any further development. The integration into Sea King arsenal is an option that is certainly possible but not simple to realize.
Germany, meanwhile, had no plans to integrate any missile systems with Sea King at all, using it solely as an anti-submarine warfare unit.

But upon a closer look at MDBA's anti-submarine helicopter armament projects we can notice the Marte ER long range lightweight anti-ship missile system, which is already integrated with the NH90 helicopter. This 345-kg anti-ship missile is guided by an active radar seeker for a range of over 100 km, and it has ground attack capability.
Potentially, it could be integrated with Sea King as well, turning the helicopter into a carrier of an interesting long-range weapon. Yet, its combat effectiveness against ground targets is still limited, as the warhead weighs only 70 kg. It should also be noted that this development originally belongs to the Italian branch of MDBA.

Another anti-ship missile that is already compatible with Sea King is the Exocet AM39 with a range of 70 km and a 165 kg warhead. The latest variety, MM40 Block 3, can reach targets up to 200 km away and can strike objects on land.

Though here, once again, the rights to this weapon belong to the French MDBA branch. Same situation with Mistral ATAM for air-to-air combat, or the anti-tank air Akeron. Therefore, technically these options are there but whether they can be the subject of an agreement between Great Britain and Germany is a rather debatable issue.
Against this background, we can only mention one more missile system that was created specifically in Great Britain at BAe Dynamics, now part of MDBA. Called Sea Eagle, it's an anti-ship weapon with a weight of 580 kg, incl. the 230 kg warhead. The operational range is 110 km.

However, this missile cannot hit ground targets. Moreover, it was withdrawn from the service of the British Navy in 2000 and is not currently present in the list of MDBA products. But it is still in service with India, where it is used by the Sea King helicopters.
In summary, the list of possible weapon options for Sea King helicopters from MDBA:
- Brimstone
- Marte ER
- Exocet AM39
- Sea Eagle
Lastly, we should note that the Sea King helicopter in itself can be considered a very powerful platform for various types of weapons, it can easily take aboard two 580-kg long-range missiles. And also, there is a prospective Brakestop project in the UK to develop a long-range, cheap and mass-produced weapon, although the timeline and progress give no optimism about its finish anytime soon.
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