Warns, “Too difficult to crack safes in skyscrapers” (8,6)

I believe the answer is:
petronas towers
But I can't explain it at all! Could you help me understand?
(Another definition for petronas towers that I've seen is " Kuala Lumpur landmark".)

I believe the answer is:
petronas towers
But I can't explain it at all! Could you help me understand?
(Another definition for petronas towers that I've seen is " Kuala Lumpur landmark".)