De or het defensieplanning?

The correct Dutch article is:

de defensieplanning

Rule Words ending in -ing: almost always de. See the rule

How to use defensieplanning

the defensieplanningde defensieplanning
this defensieplanningdeze defensieplanning
that defensieplanningdie defensieplanning
our defensieplanningonze defensieplanning
your defensieplanningjouw defensieplanning
every defensieplanningelke defensieplanning
which defensieplanning?welke defensieplanning?
a big defensieplanning / the big defensieplanningeen grote defensieplanning, de grote defensieplanning