When oil is scarce and debt is binding : policy sequencing under a severe energy supply shock

The 2026 Iran energy shock differs categorically from the 2022 episode, when Russia's invasion of Ukraine led to rerouting of oil and gas supply. The 2026 shock eliminates supply, with a volume loss exceeding 1973-74 and a full energy bill running at two or more times the crude-only estimate. Two features compound the difficulty for the euro area, United States, United Kingdom and Japan: weaker fiscal positions driving term premia higher and a live inflation regime in which tightening is now binding and costly. Narrow fiscal space may therefore force temporary monetary-fiscal coordination: targeted fiscal support to stabilise output, paired with conditional yield anchor operations that prevent financing stress from crowding out that support, while leaving the long end of the curve free to carry the inflation signal. The novelty is the inflation regime. This paper defines the conditions under which such purchases remain credible when inflation, fiscal sustainability and external adjustment bind simultaneously. Three conclusions follow. First, the binding constraint is not the mechanics of bond-buying but the market's belief in a credible exit and tightening option. Second, that belief depends on initial conditions, so coordination is not universally available: the credibility window is widest for the US, fragmentation-exposed in the euro area, foreign-exchange-cushioned in Japan and narrowest in the UK. Third, if coordination is feasible, it should be pre-committed, conditional and bounded by a published exit rule, otherwise procyclical adjustment analogous to emerging-market sudden stops becomes the default.