To go public in this way to me suggests Iran is increasing their support for terrorism in an area of American interest and this is a warning shot across their bows and to prepare the public if further action (including military) is required to sort it out.
Iran has been providing major support with training, arms, explosives and mercenaries to the Taliban in Afghanistan since the west have had troops there. My thoughts are that there has been either an escalation of support here or they are getting involved in another middle-Eastern country where America has strategic interests, Egypt, Libya and Yemen spring to mind or they are near to completing their first nuclear device.
When Iran joins the nuclear club, it is very bad news for Israel as they are a small country with concentrated centres of population, it will not take many devices to wipe them out, while Iran is the reverse, a big country with a much more spread out population.
With the worlds economic problems and political instability in the middle-east these are scary times. In the 1930's we had depression, currency wars, where everybody was trying to outdo everybody else with devaluation to make their countries more competitive (stage we are at, at the moment with low interest rates, QE and high inflation in USA and UK), trade barriers and trade wars, through selective import duties, followed finally by the Second World War. With both Germany and Japan WWII was about perceived injustices by the allies and natural resources. Germany wanted more living space, strategic natural resources, particularly oil and Japan wanted to secure all the natural resources they could as their country has very few.
Iran, North Korea and China are the worries here as history shows that dictators generally start major wars and democracies fight and win them. China is going through a major military buildup at the moment, have a number of territorial disputes with their neighbours, especially when natural resources are involved and an aggressive foreign policy. But, although they have a very large population, it is also an aging one and old people don't make very good soldiers.