The ICC is investigating the abduction of 20,000 children.

Omissions

• The 20,000 figure is a Ukrainian official estimate (Ombudsman Dmytro Lubinets has spoken of 'over 20,000' deported children), not a figure published or verified by the ICC; the Court's arrest warrants do not quantify the number of children.
• The number of children verified by independent investigators is far lower than 20,000, and Ukraine itself has stated that the true figure cannot be established while deported children remain in Russia or Russian-occupied territory.
• The figure is presented as an ICC caseload figure, which conflates the Court's investigation (which concerns deportation as a war crime/crime against humanity) with Ukrainian government estimates of the total number of abducted children.

Sources

• PrimaryInternational Criminal Court — 'Situation in Ukraine: ICC judges issue arrest warrants against Vladimir Vladimirovich Putin and Maria Alekseyevna Lvova-Belova'"Today, 17 March 2023, Pre-Trial Chamber II of the International Criminal Court ('ICC' or 'the Court') issued warrants of arrest for two individuals in the context of the situation in Ukraine: Mr Vladimir Vladimirovich Putin and Ms Maria Alekseyevna Lvova-Belova" — the warrants concern the war crime of unlawful deportation of population (children) and unlawful transfer of population (children) from occupied areas of Ukraine to the Russian Federation. No number of children is stated in the ICC announcement.
• PrimaryOHCHR — UN Independent International Commission of Inquiry on Ukraine, press release"UN Commission concludes that deportation and forcible transfer of Ukrainian children by Russian authorities" — the Commission found that Russian authorities committed the crimes against humanity of deportation and forcible transfer of children.
• SecondaryABC News (Australia) — 'UN inquiry finds Russia's deportations of 20000 Ukrainian children ...'"UN inquiry finds Russia's deportations of 20000 Ukrainian children" amount to crimes against humanity; the article also notes that "The International Criminal Court has issued arrest warrants for President Vladimir Putin and five other Russians over illegal deportation of [children]".
• SecondaryUnited24 Media — 'Russia Illegally Deported Over 20,000 Ukrainian Children'"Russia Illegally Deported Over 20000 Ukrainian Children With Another 1.5 Million At Risk" — the figure is attributed to Ukrainian Ombudsman Dmytro Lubinets.