[Goose]

I don't know that there is anything in the open that is definitive on this issue but the perception amongst informed observers is the US is making the actual decision on this. The US has always been more vocal about escalation management in ways the UK has never been. The UK allowed use of their weapons (apart from Storm Shadow) on Russian territory before the US did (apart from ATACMS).

https://x.com/ColbyBadhwar/status/1823795048141701423

I believe that the Storm Shadows use components exported from the US. These components have "End User" certificates attached. If that is indeed the case, both France and the UK would have required US permission to export these "Significant Military Equipment" (SME) to Ukraine. Obviously, that permission was given, but it may not be unconditional. The US can quietly respond "yes" to a UK transfer request without publicizing it. The UK can also place restrictions on the items transferred, possibly (but not necessarily) citing restrictions imposed by the US. I am sure that all parties involved do not want to get crosswise with their partners. If the US is unwilling, it may be a showstopper.

[Goose]

I don't know that there is anything in the open that is definitive on this issue but the perception amongst informed observers is the US is making the actual decision on this. The US has always been more vocal about escalation management in ways the UK has never been. The UK allowed use of their weapons (apart from Storm Shadow) on Russian territory before the US did (apart from ATACMS).

https://x.com/ColbyBadhwar/status/1823795048141701423

I believe that the Storm Shadows use components exported from the US. These components have "End User" certificates attached. If that is indeed the case, both France and the UK would have required US permission to export these "Significant Military Equipment" (SME) to Ukraine. Obviously, that permission was given, but it may not be unconditional. The US can quietly respond "yes" to a UK transfer request without publicizing it. The UK can also place restrictions on the items transferred, possibly (but not necessarily) citing restrictions imposed by the US. I am sure that all parties involved do not want to get crosswise with their partners. If the US is unwilling, it may be a showstopper.