Both clauses in that sentence are essential: it doesn’t matter if there are three, four, or five carriers in the Gulf, if Iran doesn’t believe we intend to use them in the near future against her nuclear program. Iran’s highest priority is developing nuclear weapons, and whatever she can wait out or endure to achieve that end, she will. Multiple carriers sitting off her coast for months on end have made no difference to her intentions, and they aren’t going to.
To intimidate Iran with military force, there are three basic requirements. First, the force must be designed for the threat. We can’t invade Iran with the 15,000 troops in Kuwait (nor, I hasten to add, should we want to invade Iran at all). It would be foolish to imply that we might invade Iran with ground troops if we clearly don’t have the forces in the area to do the job. A more realistic threat would be, say, a select embargo of Iran, which we could accomplish through military force, either more easily – with the cooperation of Iran’s neighbors and trading partners – or less easily, if we had to literally warn off the entire world with the US military.
We don’t have the forces in theater to make good on the latter threat, nor have we seriously implied such a threat. Iran therefore has no reason to behave as if this is a meaningful threat.
The second basic requirement is a strict, relatively brief timeline for enforcement and/or Iran’s compliance. A deadline of “next year sometime” is meaningless, and continued talks, without any verifiable effort at compliance, are merely a delaying tactic.
The third requirement is a realistic, executable, and meaningful threat. As long as threats are vague and only vaguely implied, Iran has nothing to respond to, and will merely continue what she’s doing with some additional amount of irritation. A threat that meets the criteria – realistic, executable, and meaningful – might be something like a military embargo of Iran’s maritime oil and gas trade. Such an embargo wouldn’t stop all oil and gas from getting into or out of Iran, but it would stop a lot, and for an operationally significant amount of time. (Eventually, Iran and her neighbors would develop ways of moving the oil and gas by other means.) This threat would require holding Iran’s naval, coastal, and air assets at risk, with the threat that if they were used they would be destroyed.
Essential to any such threat would be a next level of threat to hold over Iran, and a program of compliance for her leadership. Threats like the one outlined above gradually lose their meaning and become mere features of the regional trade system if they are not followed up with rapid, credible escalation. Saddam adapted to the military embargo of his oil and gas trade – and people at the UN were making money off of it within a few years. So was Iran, which took a big cut from the sanctions-busters who for 12 years ferried oil and other contraband to and from Iraq in small freighters and dhows.
A credible US president might approach the Iran-nuclear problem by giving Iran a short, specified amount of time to comply with a set of requirements for inspection and turnover of enriched uranium. The threat would be escalatory – from the current level of sanctions to a military attack on Iran’s nuclear and missile facilities – and would be backed up by a deployment of forces sufficient to make good the threat. The US would assume a posture of sea and air control in Iran’s southern portion during this period, clarifying that the Iranians courted destruction of their military assets if their posture became provocative.
The build-up – which should visibly include at least three carrier strike groups, one or two amphibious task forces, additional squadrons of Air Force strike-fighters, the deployment of bombers (B-2 and B-52) to Guam, and a beefed-up Army force in Kuwait, with special forces, air defense, infantry, and civil security capabilities, along with an increased missile defense footprint around the Gulf – would take as much as 45 days, but could probably be largely accomplished in 30. This would make for a meaningfully rapid timeline on which to require Iranian compliance.