It seems to me that "invincible" is used by the TMO most often with respect to countries and institutions. So if the Panama is invincible it is incapable of being conquered or subdued. Get 160 meditators and you are there.
http://www.invincibledefence.org/prev_wing/defence_research.html I take the word at face value. Sometimes I tire of strained explanations of violence in religious texts. The BG is violent. The bible is violent. The Koran is violent. I am inclined to think our species tends towards violence against itself and religions would be much more spiritual if the writings were less violent. Me, I am strong, I am invincible, I am woman!