An intermediate-range ballistic missile (IRBM), in the most basic terms, is a ballistic missile with a range between 1,400-5,499 km (1,500-3,437 mi). As ballistic missiles were first developed, IRBMs were feasible before the longer-range intercontinental ballistic missiles, although ICBMs replaced IRBMs in the arsenals of Russia and the United States. IRBMs, both land and submarine launched, remained the longest-ranged missiles of Britain and France. China has plausible requirements both for IRBMs and ICBMs.
Britain and France needed to engage targets within a roughly continental region. This is also the case for the Israeli Defense Forces with its Jericho III, and is also of interest for other Middle Eastern powers, as well as India and Pakistan.
A modern IRBM is faster than theater ballistic missiles although slower than an ICBM, thus presenting a more difficult problem for theater-level ballistic missile defense (BMD).