- ICD 203
- Intelligence Community Directive 203: the US intelligence agencies' rules for analysis. It ties words for likelihood to numbers (likely means 55-80%). This page uses its scale.
- The PLA
- The People's Liberation Army: China's armed forces (army, navy, air force and missile force), run by the Communist Party.
- Readiness, a readiness goal
- Readiness is how prepared forces are to fight at short notice. A readiness goal is the date by which an army aims to be able to fight if ordered: not a date when war is expected.
- The US commands
- The US military's regional commands: Indo-Pacific Command (the Pacific and Asia), Central Command (the Middle East) and Northern Command (the defense of North America).
- The Revolutionary Guard (IRGC)
- Iran's Islamic Revolutionary Guard Corps: a military force loyal to Iran's Supreme Leader, separate from its regular army, with its own missiles and its own operations abroad.
- The Supreme Leader
- Iran's highest authority, above its elected president and in command of its armed forces.
- The Houthis
- An armed movement that controls much of Yemen. Backed by Iran, it has attacked shipping and Saudi Arabia.
- Hormuz
- The Strait of Hormuz: the narrow sea passage between Iran and Oman, the only sea route out of the Gulf, used by much of the world's oil.
- FORTRESS
- A Pentagon program launched on 30 Sep 2026 to make every major US base produce its own power, apart from the public grid.
- Golden Dome
- A planned US shield against missiles and drones, partly in space. Its cost estimates run from $185bn to about $1.2 trillion (question Q6).
- Interceptors, Patriot
- Missiles that shoot down incoming missiles or drones. Patriot is the main US system for it.
- Volt Typhoon
- The name US agencies give a Chinese state hacking group that has hidden inside US water, power, transport and communications networks.
- Pre-positioning
- Getting quietly inside an enemy's networks in peacetime, so that an attack can be launched later, in a crisis.
- CISA
- The Cybersecurity and Infrastructure Security Agency: the US agency that warns about attacks on networks and essential services, and helps defend them.
- Attribution
- A government officially naming who was behind an attack. For sabotage and cyber attacks it can take months.
- Proxies
- People or groups who act for a state so it can deny being involved, often criminals or locals hired for one job.
- Pressure short of war (the gray zone)
- Coast-guard clashes, cyber attacks, sabotage, drones and threats, kept below the line that would start a war.
- The first island chain
- The arc of islands from Japan through Taiwan to the Philippines that closes off China's coastal seas. US strategy is to defend along it.
- Blockade, “quarantine”
- A blockade stops ships reaching a place by force, and is an act of war. A “quarantine” is a softer version run by coast guards, inspecting or turning back ships, which China could use against Taiwan.
- Treaty allies
- Countries the US has promised by treaty to help defend, such as Japan, South Korea, the Philippines and the NATO members.
- The Taiwan Relations Act, the Six Assurances
- The 1979 law under which the US provides Taiwan with arms for its defense (it does not promise US forces), and the US promises to Taiwan of 1982, including that the US did not agree to consult Beijing about those arms sales.
- APEC and the G20
- Yearly summits of world leaders: APEC for the Asia-Pacific economies (in Shenzhen, China, on 18-19 Nov 2026) and the G20 for the biggest economies (near Miami on 14-15 Dec).
- The midterms
- US elections held halfway through a president's four-year term, for the whole House and a third of the Senate. In 2026: Tue 3 Nov.
- The DMZ
- The demilitarized zone: the guarded strip between North and South Korea since 1953.
- ICBM
- An intercontinental ballistic missile: a long-range missile, often nuclear-armed, that can fly from one continent to another.
- Arms control, New START
- Treaties that cap and inspect nuclear weapons. New START, the last one between the US and Russia, expired on 5 Feb 2026.
- Deterrence
- Preventing an attack by making the attacker expect it to cost more than it gains. A nuclear deterrent does this with the threat of a nuclear reply.
- Détente
- An easing of tension between rivals.
- Doctrine
- A country's or a force's stated rules for when and how it fights; for nuclear weapons, when it would use them.
- Alert levels
- How ready nuclear forces are to launch. Raising them is a warning sign.
- Battlefield nuclear use
- A smaller nuclear weapon used against troops in a war zone, or as a one-off warning, rather than on cities.
- Mobilization
- Calling up reserves and putting a country's forces and industry on a war footing.
- Article 5
- NATO's promise that an armed attack on one member is an attack on all; each member then decides how to help. Used once, after 11 September 2001.
- Kaliningrad
- A piece of Russia on the Baltic coast between Poland and Lithuania, cut off from the rest of Russia. Home to Russia's Baltic Fleet.
- Reservists, the Selected Reserve and the IRR
- Part-time service members who train regularly (the Selected Reserve), and former service members who can still be called back (the Individual Ready Reserve). Recall never covers anyone who has not served.
- Selective Service, registration
- The US agency that keeps the list of men who would be called if Congress ever brought back a draft. Registering is not being drafted.
- Conscription, the draft
- Making people serve in the military by law. The US last drafted men in 1972-73; it would need a new law from Congress.
- The betting crowd, the forecasting crowds
- Polymarket is a website where people bet real money on whether something will happen; the price works as the crowd's odds (10% means about a 1-in-10 chance). Metaculus is a site where many people forecast and are scored on accuracy. We use them only as a cross-check.
- “Department of War”
- A second name the Pentagon has used since a September 2025 order. Its legal name is still the Department of Defense unless Congress changes it.
- Red team
- Arguing hard against our own judgments to find their weak spots. Where one did not survive, we changed it.