True in the constitutional sense intended here. The UK government has the power to make international treaties under its prerogative powers, and Parliament generally does not get to approve, reject, or amend the treaty itself; separately, the government can deploy armed forces abroad without Parliament’s consent under the royal prerogative. So the UK can choose key parts of its relationship with the US, including whether to enter agreements and whether to use force. Sources: House of Commons Library, "Parliament's role in ratifying treaties"; GOV.UK, "Waging war: Parliament's role and responsibility". (commonslibrary.parliament.uk)