As someone with a Ph.D. in military history, let me say, first, foreign nations *have* invaded the U.S. from the sea (during the Revolutionary War & the War of 1812), and, second, the subsequent paucity of invasions had nothing to do with “gun owners” but a lot to do with oceans. https://t.co/AhICQqCyUh

— Mark Pitcavage (@egavactip) March 4, 2019