I think the power of nukes comes from not having an opportunity of using them. It does not mean that the country will be free from wars or other means of conquest, but acts as a deterrence to other nuclear attacks and prevents escalation of war. Let's remember that when Israel was being smoked by a coordinated attack from Syria, Egypt and Jordan, during the Yom Kippur war, the threat of nuclear escalation made the US to broker an agreement with Israel's neighboring states. However, nuclear deterrence does not prevent other forms of war, like assassination, sabotage, precision strikes or proxy wars.

Iran is very close to having the ability of manufacturing nukes, though. It has advanced missiles, Uranium enrichment facilities, and abundance of stocks of enriched Uranium. What Iran may lack is technology for miniaturizing the nuclear payload (or not, if they got it from another country or if they stole the tech through espionage).