Hypersonica, meanwhile, is already gaining experience through Nightfall, a British-funded project to develop missiles for Ukraine. According to the briefing, some of that work could help the startup develop a more advanced German-British weapon.

Another complication will be finding out what role France will play — if at all.

When Chancellor Friedrich Merz and President Emmanuel Macron met in July, they agreed to explore cooperation with Britain on long-range weapons, specifically highlighting that ArianeGroup, the Franco-German rocket manufacturer, could play a role.

However, political agreement between European governments does not automatically settle industrial arrangements.

The ministry briefing says talks about involving ArianeGroup in developing a booster — the rocket component that would propel the hypersonic weapon into flight — proved difficult because of limited rights to use the technology. The document does not specify what those restrictions entail.

For Britain and Germany, the next step is to turn these plans into firm commitments. Officials have discussed initial agreements to advance the missile project before the end of the year, separate documents seen by POLITICO show, although it remains unclear whether any will be signed during Streeting's visit.