I'm wondering which of the following sentences is correct:
- They realized that if the threat WAS not contained, it could endanger the nation."
- They realized that if the threat WERE not contained, it could endanger the nation."
My understanding is that the subjunctive "If X were" is used for a counterfactual to a present situation. But here, the threat not being contained is a real possibility being considered in the past.
If the main clause were written in the present tense, "to be" would be present indicative: "If the threat IS not contained." So I'd think it should be past indicative when the main clause is past tense. Am I right?