De or het ijskastdiplomatie?

The correct Dutch article is:

de ijskastdiplomatie

Rule Words ending in -tie and -sie: almost always de. See the rule
Meaning (Dutch) zeer koele vorm van diplomatieke relaties tussen twee of meer landen

How to use ijskastdiplomatie

the ijskastdiplomatiede ijskastdiplomatie
this ijskastdiplomatiedeze ijskastdiplomatie
that ijskastdiplomatiedie ijskastdiplomatie
our ijskastdiplomatieonze ijskastdiplomatie
your ijskastdiplomatiejouw ijskastdiplomatie
every ijskastdiplomatieelke ijskastdiplomatie
which ijskastdiplomatie?welke ijskastdiplomatie?
a big ijskastdiplomatie / the big ijskastdiplomatieeen grote ijskastdiplomatie, de grote ijskastdiplomatie

Meaning, plural, diminutive, pronunciation and translations: WikiWoordenboek (Dutch Wiktionary) (CC BY-SA 4.0). Example sentences: Tatoeba (CC BY 2.0 FR).