The suggestion that a sovereign state cannot be sovereign when it is party to a treaty is inherently absurd, as the modern notion of a sovereign state is that it is a state capable of entering into a treaty

The modern nation state, at least in the west, derives in part from the treaty of Westphalia: https://en.wikipedia.org/wiki/Westphalian_sovereignty

To say that being party to a treaty negates being a sovereign state is to, well, be ignorant of four hundred years of history, law and diplomacy

Even the EU, which can in certain circumstances also be a party to certain international agreements, can only do so because of the prior terms of the two treaties of EU between the 27 sovereign member states

Being able to freely enter into treaties is what sovereign states *do*

That is why, for example, Canada, Australia and New Zealand insisted on being party to the Japanese instrument of surrender in 1945

The British Empire would not sign on *their* behalf, thank you very much

The UK government's insistence that sovereignty means never being bound by a treaty freely entered into is...

...akin to saying 'freedom to contract' means you should never enter into contracts.

Daft.