There is a strong possibility that Iran is being used as an instrument against the Sunni States; and as such, many dangerous concessions may be made to achieve that goal. But what kind of concessions are we talking about: nuclear programme, expansion of influence or both? Either kind is dangerous if there's no plan to keep the Persians under control, after the implementation of the plan is complete.
Looking at the map of the Middle East (ME), it is relatively easy to see that Iran's influence in the region is beginning to be cemented: Hezbollah in Lebanon and in Syria, the Houthis in Yemen, Hamas and the Islamic Jihad in Gaza, and the Iranian presence, to support the Shiite militias, in Iraq where it is not only being successful in fighting off the Islamic State but also winning the sympathy of the locals:
"They [Shiites] are good, (..) If someone is sick, they'll take them to the doctor, even at 2 or 3 in the morning (..) If it weren't for them, ISIS would have slaughtered us." (Jamid [a Sunni]; in 'Iraqi, allied forces try to win back Tikrit, win over hearts and minds of residents', CNN, March 13, 2015)
Of course, Iran does not need the West's permission to expand its power in the ME; however, in politics it is customary to try to hinder the expansion of a country, if it suits one's national interests (and those of its associates); therefore the lack of such effort, in this case, indicates that Iran has been given some margin of manoeuvre – an idea supported by the information that "The nuclear deal with Iran may end up being a verbal understanding with nothing written down".
By gaining ground and stretching its scope of influence, Iran is slowly decreasing the power of Sunni countries (Saudi Arabia, Qatar, Kuwait and others). Why would the West pursue such a plan? Because the mentioned countries had an opportunity to scale back their subversive activities but failed to seize it.
For instance, Saudi Arabia and Qatar are known for sponsoring the spread of Islam, radicalism and terror groups worldwide, yet because they have injected a lot of capital in western economies, it is politically inconvenient to impose sanctions on those countries (or even rebuke them in public). Kuwait has been under the radar for being the channel through which funds that fuel terror groups flow; but it seems ludicrous to impose sanctions on it (or even rebuke it in public) when millions of dollars have been spent on a PR campaign to render it a victim and then liberate it. Thus, western politicians decided that the best way to challenge the Sunni power is to use their foe against them – a smart yet dangerous move.
The Danger Behind the Plan
But what if Sunnis and Shiites are not really foes despite appearances?
The Sunni Camp feeds the illusion that they are in open sectarian war with the Shiites (and to that end they are willing to sacrifice the lives of their own people), to have access to the western weapons market. Western Intelligence suspect the same but it suits politicians to sell weapons to Sunni countries because it helps them stabilise their economies; therefore, Sunnis buy billions of dollars-worth of weaponry to protect themselves against a possible Iranian threat. But looking at the expansion of Iranian activities in the ME, we are not seeing those weapons being widely used against the Iranian proxies – last Thursday, however, it was reported that a Saudi-led coalition was air-striking the Houthis, in their home province Saadah (hitting an arms depot and the airport); and Taiz (hitting the al-Tariq military base); but this kind of offensive is not new (the Saudis engaged in a similar operation in 2009, albeit more limited in scope) and it has nothing to do with sectarian conflicts, but with politics (Saudi Arabia supports President Hadi). Nevertheless, due to the nuclear talks with Iran, now it's convenient to pass the image that the conflict in Yemen is a Sunni vs Shiite type of crisis; which is too simplistic an explanation.
The Shiite Camp feeds the deception that they are in a sectarian war against the Sunnis (although they are far more subtle about it and often portray themselves as the victims of the Takfiris), but they do strike deals with them if needed be (e.g. Iranian accords with Hamas and the Sunni Government of Sudan to pass weapons to the Houthis); for in spite of everything, under the Iranian perspective, they are all after the same thing: the expansion of Islam throughout the world.
Iran seeks to build nuclear weapons (reason why it maintains strong ties to China, North Korea and Russia), designs its own planes, boats and submarines; conducts military exercises and is gifted with brilliant strategic minds. Their technology may not be the best (when compared to others') but their SWOT Team is a force to be reckoned with.
The Iranian leadership, last Thursday, warned that the Saudi intervention "will lead to spread of terrorism and extremism in the Middle East region” - another incongruence (since Iran plus the Saudi/Qatar camp have been doing just that for decades); therefore, deception must be at play here.
1- If both camps are in bed together, and the West is tacitly shifting sides, how is the threat being fought exactly?
2- If the conflict in Yemen is indeed a proxy war against Iran, why is Iran so relaxed (indicated by their nonsensical comments about the Saudi-led Operation Decisive Storm)?
3- Is it wise to totally discard the hypothesis that Yemen is being used as a test field (to test coordination, possible scenarios, the acquired weapons, units cohesion etc)?
“Let us not be afraid to see the hatred that consumes the lives of hundreds of thousands of Arabs who sit around us and wait for the moment when their hands will be able to reach our blood.” -- Moshe Dayan