SinoSoldier
Colonel
I can agree that it is normal for fighting forces to experience losses and/or setbacks, and in the case of Saudi Arabia this is their first major independently led operation so it's not unreasonable to expect a less than stellar first performance.
There is no reason to bring the PLA or the Korean War to illustrate your point at all given the difficulty in having an accurate analogy.
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As for Saudi Arabia's performance in Yemen, I do not think it is fair to say that they lack a "will to fight" or anything like that, but rather that they've already picked the low hanging fruit (using their overwhelming air power to drive initial successes), but now they are finding it difficult to fight a ground war against a force of irregular guerrillas despite their vast technological advantages.
That is not too different to any other conflict of this kind involving boots on the ground.
There is also Saudi Arabia's inexperience with their weaponry to consider. As far as I know, it is the first time the Saudi military dedicated modern military assets to the battlefield in large quantities and the rate at which they are losing tanks to the enemy is quite indicative of that.