http://general-terms.thesaurus.ekt.gr/vocabhttp://general-terms.thesaurus.ekt.gr/vocab?tema=12175national defence http://general-terms.thesaurus.ekt.gr/vocab?tema=12175 defensive operations NT http://general-terms.thesaurus.ekt.gr/vocab?tema=12175 passive defence NT http://general-terms.thesaurus.ekt.gr/vocab?tema=12175 defensive systems NT http://general-terms.thesaurus.ekt.gr/vocab?tema=12175 defence BT