Re: Jet Engine
Precisely. Quick calculation for an Arleigh Burke Class Destroyer with state of the art AEGIS air defences:
Cost of ship: $1.8 billion
Give it maximum possible defences (2 x RIM-116 short-range missiles and 2 x Phalanx CIWS) and perfect accuracy. You can take out 82 close in threats. Anything else needs to be stopped by the SM-2 and SM-6 missiles further out. Let's assume that the entire VLS is quad-packed with exactly the right loadout (no chance). With yet more impossibly perfect accuracy, you can take out 384 targets. Total 466. Anything above that and the ship is dead, even in this defenders dreamworld.
Cost of Kh-31 anti-ship missile: $0.5 million.
Cost of 500 Kh-31s: $250 million.
You can, therefore, take out the ship spending only 14% of what it cost to build it.
I'm not suggesting that's workable military strategy, you would need an unassailable base to launch all those missiles from for a start, but that doesn't change the fact that big, expensive targets need to achieve and maintain incredible (quite literally) levels of performance in the face of large numbers of (relatively) low tech threats. Personally, I strongly suspect that even 50 Kh-31s inbound means a dead ship.