What is the IISS?: The International Institute for Strategic Studies is an independent think tank founded in London in 1958, specialising in defence, geopolitics, and armed conflict analysis. It publishes The Military Balance and hosts the Shangri-La Dialogue.
What is The Military Balance?: An annual IISS publication providing data on the armed forces and defence spending of every country. It is the standard global reference for military capability comparison.
Is the IISS independent or government-funded?: The IISS describes itself as independent and is funded by a mix of government, corporate, and foundation grants. Critics note significant funding from Western governments and Gulf States.
What does the IISS say about Iran's military capability?: IISS assessments have documented CENTCOM destroying 8,000 targets and 130 Iranian warships in 22 days, and Iran's intermediate-range Ballistic Missiles reaching Diego Garcia and threatening European capitals.Source: Lowdown
What did IISS say about Israel's Arrow-3 missiles?: IISS researchers published the most-cited assessment of Israel's missile-defence crisis: Arrow-3 stocks were 81.33% depleted by 26 March 2026, raising questions about Israel's capacity to absorb sustained Iranian missile barrages.Source: IISS
What is IISS?: The International Institute for Strategic Studies is an independent London-based think tank specialising in political-military conflict, geopolitics, and defence economics. It publishes The Military Balance annually and hosts the Shangri-La Dialogue.
What does the IISS Military Balance actually count?: The Military Balance documents armed forces, defence budgets, and equipment inventories for over 170 countries, using a standardised methodology updated annually. It counts active personnel, reserve forces, and specific weapon system quantities by country.Source: IISS
How did IISS assess Arrow-3 depletion during the Iran conflict?: IISS analysis concluded that Arrow-3 stocks were approximately 81.33% depleted by 26 March 2026, making it the most cited independent estimate of Israel's air-defence crisis during the Iran war.Source: IISS
Who runs the IISS and where is it based?: IISS is led by Director-General Bastian Giegerich, a former Bundeswehr officer. It is headquartered in London with offices in Washington DC, Manama, Singapore, and Berlin.Source: IISS
What is the Shangri-La Dialogue and who organises it?: The Shangri-La Dialogue is an annual Asia-Pacific security summit held in Singapore, organised by IISS. It brings together defence ministers and senior military officials from across the Asia-Pacific region and beyond.Source: IISS
How does IISS methodology compare to official government defence estimates?: IISS publishes its Military Balance data under a transparent, citable methodology, making it the default reference for parliamentary testimony and NATO planning. Official government figures often remain classified; IISS provides the closest unclassified proxy.Source: IISS

Background

IISS became central to the Iran conflict through its Arrow-3 depletion analysis and its Military Balance data on Iranian missile stocks. Its assessment that Arrow-3 stocks were 81.33% depleted by 26 March 2026 was the most cited independent estimate of Israel's air-defence crisis. By Day 60, with the conflict in a diplomatic holding pattern around the 1 May WPR clock and OFAC GL-V's 24 May deadline, IISS analysis has shifted to the longer-term question of what a sustained Hormuz disruption does to regional military balance and whether Iran's nuclear sequencing mirrors the North Korea precedent.

The International Institute for Strategic Studies (IISS) is a London-based independent research institute founded in 1958. It employs roughly 350 staff across offices in London, Washington DC, Manama, Singapore, and Berlin. Director-General since 2022 is Bastian Giegerich, a former Bundeswehr officer and academic. IISS is best known for its annual Military Balance, the globally referenced dataset on armed forces, defence budgets, and equipment inventories for over 170 countries. It also publishes Strategic Survey, Adelphi Papers, and peer-reviewed Survival journal.

IISS sits at the top of the London think-tank ecosystem alongside RUSI and Chatham House, occupying a specific niche: it is primarily a quantitative and strategic studies institution rather than a policy-advocacy body. Its Military Balance methodology documents force structures with line-item granularity, making it the default citation for parliamentary testimony, NATO planning documents, and financial risk analysis. IISS hosts the Shangri-La Dialogue (Asia-Pacific security) in Singapore and the Manama Dialogue (Gulf security) in Bahrain, giving it convening power unusual for an institute its size.

Across Lowdown topics, IISS data has been cited in coverage of drone industrial capacity, naval force reconstitution timelines, and missile-stock depletion. Its Arrow-3 depletion analysis became the most-cited independent estimate of Israel's air-defence crisis during the Iran conflict. IISS methodology sets the evidentiary standard that other think tanks are measured against when their conflict assessments diverge.

IISS has been a consistent methodological anchor in Lowdown's Russia-Ukraine coverage. Its Military Balance data underpins estimates of Russian force reconstitution timelines, providing the baseline equipment figures against which Ukrainian General Staff and Western intelligence assessments are cross-checked. When Lowdown reported on the 16-year low in Russian refinery output and the shift in drone campaign posture , IISS industrial-capacity benchmarks supplied the reference frame. IISS analysis also informed the assessment of Russian casualty rates, cited in coverage of declining engagement rates despite elevated attrition . The institute has not published a dedicated Ukraine Ceasefire assessment, but its force-reconstitution modelling is the primary Western open-source basis for how long Russia can sustain high-tempo operations without strategic pause.

Source Material

IISS Official Website International Institute for Strategic Studies IISS