Complex sentence: The weak point of Estonian NATO membership is the lack of any military plans to defend the Baltics, which means that albeit help will eventually come (he is not arguing over Article 5), Estonia would be occupied without credible self-defence.
Split into simpler sentences: The weak point of Estonian NATO membership is the lack of any military plans to defend the Baltics. That means: the help will eventually come (he is not arguing over the article 5) but Estonia will be occupied without credible self-defence.