The word secure means many things, but its not a common word in a civilian's vocabulary so most people don't think about it, but lets look for a second, and see what the military thinks it means.
If you tell the Air force to secure something, they're going to buy it, because to them, secure means procure.
If you tell the Army to secure something, he's going to build a fort around it and guard it.
If you tell a Marine to secure something, he's going to look at the intel, plan a covert incursion, kill everything and everybody in sight, and now whatever it was you told him to Secure now belongs to him and him alone.
If you tell a Sailor to secure something.... we're going to turn it off and go home
But wait! What does this mean in an operational sense!? Lets say you have a vital oasis out in the middle of some middle eastern desert, what happens if you tell someone to secure it?
If you tell the army to secure it, they're going to bomb the hell out of it, build a fort in the middle of it, ask where the water went, and guard it anways.
If you tell the Marine Corps to secure it, they'r going to poison the water so none of the animals can drink from it, kill the animals anyways and then cut down all the trees so nobody can hide in them... this oasis is now a marine base.
If you tell the Nay to secure it, they'll send the Marine corps to do it, because the oasis is land locked, and devil dogs like getting hot and sweaty for no particular reason.
Now, on the other hand, if you tell the Air force to secure it, they'll contact whichever country supposedly owns it, buy it for them for three times what its worth, and build a golf course on it (even though its 1000 miles from humanity) with a strawberry daquiri machine on each Tee, then ask why the Navy hasn't made it yet.