Both sides, in good faith

The strongest fair case each way — we don't pick a winner.

The case for

Supporters argue that helping Ukraine build its own long-range strike capability is a proportionate and necessary response to an unprovoked invasion, particularly as Russia intensifies attacks on civilian targets such as the shopping centre struck on Friday. They contend that a sovereign nation has the right to defend itself and to strike the military infrastructure enabling those attacks, and that sharing technology such as Scalp component data, alongside air defence and counter-drone equipment, strengthens deterrence and could hasten a negotiated end to the war by denying Russia the assumption that its aggression carries no cost. On this view, visible, high-level solidarity, such as a first foreign visit to Kyiv, also reassures allies that Western commitment will not waver as the conflict drags on.

The case against

Critics, while often sympathetic to Ukraine's plight, warn that transferring the means to produce long-range missiles domestically marks a significant escalation that risks deepening direct confrontation between Britain and Russia, especially as Moscow has explicitly framed such moves as justification for retaliation. They argue that governments should weigh carefully whether each new step, from missile blueprints to interceptor requests, brings the war closer to resolution or simply raises the stakes and prolongs the fighting, with unpredictable consequences for wider European security. Some also caution that domestic political capital and resources devoted to expanding a foreign military role should be weighed against pressing needs at home, and that decisions of this magnitude warrant full parliamentary and public scrutiny rather than being presented as a fait accompli during a leader's first overseas visit.