Torotorella,
The truth is Iran serves as a valuable tool for the Americans and, the Arabs and the Israelis.
Iran's belligerence allows others to pursue their interests.
For the Americans, it gives them an excuse to maintain strategic control of a vitally important region (though they've made a mess of this).
Iran's involvement in Syria, Lebanon as well as Caspian also acts as foil to Russian and Turkish aspirations in the region, neither of which are in the American national interest.
For the Israelis, it takes away attention from the Palestinian issue and also endemic Israeli corruption and government ineptitude.
And not just little ol' socialist me saying this – these articles are by an ex-member of the CIA/National Intelligence Council.
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Of course the confrontation with USA/Israel also serves Iranian government interests.
Get rid of Iran as a player:
1. US can no longer claim any need to maintain significant presence in the region. Indeed save Syria the whole are is under nominal US "guidance."
2. US support for Islamo-fascist allies such as Saudi Arabia and UAE becomes increasingly difficult to justify.
3. Attention refocuses on the Israeli-Palestinian issue and particularly Israeli land repossession to appease ultraconservative Haredis and their quest to recreate ancient Israel.
4. American support for Israeli military also becomes somewhat questionable. Egypt and Syria's militaries are no a threats (well Syria's hasn't been since 1982).
Without Iran, Syria and also Hezbollah's capabilities degrade.
Hard to justify US taxpayer subsidised F-35s if there is no significant threat.
5. For Iran and Shias in general, any US win is a Sunni win and will have ramifications for Shia living in Saudi Arabia (already persecuted), Iraq and elsewhere.
6. If current Iranian regime collapses or is destroyed, the country will be preyed upon by others – the Russians, the Turks and the Saudis.
Thus destruction of Iran's regime is against everyone's interests.