If a missile has a range more than 300km and can carry explosives more than 500kg, you are not supposed to sell it under MTCR (missiles’s technology control regime) rules.
The MTCR is not a treaty and does not impose any legally binding obligations on partners (members). Rather, it is an informal political understanding among states that seek to limit the proliferation of missiles and missile technology.
Missile Technology Control Regime - Wikipedia
15. Are the MTCR’s Guidelines binding?
No – the MTCR is not a treaty and does not impose any legally binding obligations on Partners. The only activity prohibited absolutely by the Guidelines, to which all 35 Partner countries voluntarily subscribe, is the export of production facilities for Category I MTCR Annex items.