I am a little confused by this:
( local8now.com/home/headlines/15834547.html )
"The Pentagon says it should be able to confirm within 24 hours if the tank was hit. Debris should be raining back down on Earth immediately and the Pentagon says nearly all of it will fry up on re-entry.
The missile had to be modified from its original purpose of knocking out incoming missiles. Officials estimate the mission cost around 30 million dollars."
A missile is not a purpose. So a missile could not be modified from one purpose to another purpose. (But an objective could be modified from one purpose to another, since an objective is similar to a purpose). So could the marked part be wrong? For the pattern "X is modified from Y", I thought that either 1) X and Y must be approximately the same type of "thing" or 2) Y must be an intrinsic property of X. In my question, a rocket and a purpose are not close to being approximately the same type of thing. Nor is a purpose an intrinsic property of a missile. Hence my confusion.
Strictly speaking, you are absolutely correct. However, this is a perfectly acceptable and completely understandable shorthand for "...modified in such a way as to be able to fulfil a function different from its original purpose....". I hope you will agree that the shorter version is better.
I'm not a teacher of English, but I have spoken it for (almost) all of my life....