The claim is accurate in constitutional terms. In an official UK government paper, the government said that under the royal prerogative it can declare war and deploy armed forces abroad without Parliament’s consent; the 2011 Cabinet Manual likewise recorded that the government could deploy the Armed Forces and that, by 2011, a Commons-debate convention had developed before troops were committed except in emergencies. So the UK government could choose whether or not to go to war, although that did not mean Parliament had a guaranteed vote in every case. (gov.uk) Sources: GOV.UK, “Waging war: Parliament’s role and responsibility”; UK Cabinet Manual (1st edition, October 2011); UK Parliament Hansard, 10 March 2011.