Smoke rises over residential area following an Israeli attack on Beirut, Lebanon on April 8, 2026. —Houssam Shbaro—Anadolu/Getty ImagesDuring the early years of the Cold War, the “domino theory” drove foreign policy. It argued that if one country went communist, its neighbors would be next, so the imperative was to intervene early and hard. The result was a series of military commitments, culminating in Vietnam, that discredited the theory.Today, the world is suffering from a new version of the domino effect, marked by the spread of instability rather than of communism. The world is much more interconnected than 60 years ago, and from energy prices to AI-generated deepfakes to flows of people, the speed of transfer is viral. Yet in place of Cold War paranoia about knock-on effects, there is complacency. The war in Iran exemplifies the dangers. The newly announced two-week ceasefire with Iran is a welcome pause—but it is partial, fragile, and will not end the domino effect of conflict the region is currently experiencing in countries like Lebanon and Syria. In fact, the ceasefire underscores how fragmented this crisis has become. Even if it holds, the longer-term consequences demand urgent mitigation.The consequences of the war were never going to be confined within Iran’s borders, yet the shock absorbers have not been put in place to mitigate the damage. The immediate impact of the war in Iran is regional, but the danger is global. Across a swathe of Middle Eastern countries, bookended by Afghanistan and Pakistan in South Asia and Sudan in Northeast Africa, there are already 115 million people in humanitarian need and 40 million forcibly displaced. Over 4 million more people have already been forcibly displaced by the wars in Iran and Lebanon. The closure of the Straits of Hormuz, with energy prices up, fertilizer supplies blocked, and humanitarian supplies stuck in the Humanitarian Hub in Dubai, hits everyone but hurts the most vulnerable the hardest. I have just seen this for myself in Lebanon and Syria, visiting people displaced by the conflict and talking to government ministers and diplomatic representatives. Last year, these countries started a long process to rebuild. The former finally established a credible government and set out to build a new political settlement. The latter unseated a hated dictator and pledged a welcome for all Syrians.The year ahead now promises multiple serious reverses. Two countries who have been determined to stay out of the conflict, confront a vortex of economic instability and unmet expectations, while they are still dealing with the humanitarian consequences of previous conflicts. Lebanon is the most urgent case. International neglect has compounded national division. There is popular anger in all directions—at Hezbollah for escalating conflict, at Israel for occupation of Lebanese land, at the government for its lack of agency, and at the international system for inaction.We estimate that nearly 1,500 people have been killed in the last four weeks (including a former staff member of my organization, her husband, and her three-year-old son, all killed in an Israeli airstrike). Over 1 million civilians have been displaced by fighting in the south of the country, constituting around one-fifth of the country’s population. Around 140,000 Lebanese are in “collective shelters” like schools and football stadia.Economic growth that last year tallied 5% has gone into reverse. Cash payments to Lebanon’s poorest ($145 for a family of five) do not come close to covering the cost of the basics for a month. A nurse working for one of our partners told me in Beirut, “It is really hard to have a future here. It’s just way too hard to plan.” Conflict-affected states like Lebanon and Syria face a permanent struggle to keep their heads above water. The challenge is to tackle short-term humanitarian needs that incubate resentment and instability while at the same time acting for longer-term national economic and social development. Focus only on the former and aid dependency results. Focus only on the latter, and you lose the people. For the ceasefire to be effective, there must be a humanitarian lane through the Straits of Hormuz. This needs to liberate the humanitarian supplies trapped in Dubai and also allow fertilizer supplies—30% of the global total—which are critical to food production. The IRC has calculated that June is the month when a “ food security time-bomb” will begin to explode, as weak harvests resulting from stalled fertilizer deliveries plunge millions of people into extreme hunger.Plus, we must double down on macro-economic support for countries welcoming back displaced people. Around 1.5 million Syrians have returned to their country from Lebanon over the last 15 months. The exultation of homecoming that was described to me is currently matched by material penury. The World Bank and IMF meetings in the middle of April are a good place to deliver the macroeconomic boost that is essential.New research from the Center for Global Development shows the clear link between aid cuts and conflict. Within the last year, conflict and conflict-related deaths have risen 5%. Part of the solution must be to restore aid cuts that have devastated the most basic elements of the social safety net, and ally social support to small-scale business development. In Syria and Lebanon, the cuts to IRC programs alone in the last year have been worth over $10 million. These cuts are the incubators of the next conflict. Fourth, change the way the aid system works to deliver better in the toughest places. The World Bank Spring Meetings will soon take place. Its new strategy for fragile states calls for a new partnership with community-based organizations to ensure effective delivery in a cost-effective way. This needs strong support from its shareholders.I was told by a civil society activist in Damascus: “We want a future for our kids. We don’t want blood.” That won’t happen by accident. The domino effect is alive and well today. It is negative and destructive, and we need to act on it urgently.