It's misattributed to Bastiat, but it was actually written by a left leaning Philadelphian named Otto T Mallery in a book written in 1943:
In addition to his work in recreation, Mallery is also known for his economic writings. He authored "Economic Union and Durable Peace," published in 1943, which includes a quote often mistakenly attributed to Frédéric Bastiat: "If soldiers are not to cross international boundaries, goods must do so. Unless shackles can be dropped from trade, bombs will be dropped from the sky".
And my question for Mallery and all the other globalist free traders is this:
If that statement is true, why, in the age of unlimited US "free trade" have we been at war pretty much since WWII and have troops in over 100 countries around the world?