The target of the Saudi action is not Lebanon.  It is not Hezbollah.  It is Iran.
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Trump wants nothing more than an excuse to start a shooting war with Iran.  This is what Israel wants.  It is what Saudi Arabia wants.  If they can start a war with Iran, (they think) they can break up the Iranian nuclear deal.
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That is the point.
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The Saudi armed forces have never yet won a shooting war against a competent adversary.  Saudi Arabia is an accidental nation that the British should never have created.  In its brief history it has been of benefit to nobody.  It has thwarted democratic reforms in almost ever Arabic-speaking country.
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It is now using its expensive high-tech weaponry to bomb defenceless civilians.  Saudi Arabia is engaged in an enormous war crime in Yemen, where it is using cholera and famine as weapons of war.
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The young Prince needs to take a foreign holiday.  Pretty soon there are going to be people waiting for him in The Hague.