Translation guide
In Japanese, 'international organization' is most commonly expressed as 国際機関 (こくさいきかん). The term 国際組織 (こくさいそしき) is also used but is less common. When referring to specific well-known organizations, the English name or abbreviation is often used directly.
Referring to any international body, such as the UN, WHO, or NGOs.
The standard and most common term for 'international organization', especially intergovernmental ones.
国連は最も重要な国際機関の一つです。
The United Nations is one of the most important international organizations.
Also means 'international organization', but slightly less common than 国際機関. Can be used for both governmental and non-governmental bodies.
その国際組織は環境保護に取り組んでいます。
That international organization is working on environmental protection.
When the organization's name is widely recognized, using the English name or abbreviation is natural.
For organizations like the UN, WHO, NATO, etc., Japanese speakers often use the English abbreviation or full name in katakana or as-is.
WHOは国際機関です。
The WHO is an international organization.
彼はユニセフで働いています。
He works for UNICEF.