Israel has been planning it for years as Iran says their goal to destroy Israel
I'd like to build on what you have stated.
What the Ayatullah wants more than life itself is to assume the role of the prophet of Allah. The problem, of course, is that mainstream Islam has cancelled the idea of any more prophets popping up because then all Islamic leaders would have to bow to him. Now, if anyone comes along claiming to be a prophet, he can be executed as a blasphemer, i.e. everyone knows that Mohammed is the last prophet.
However, in the history of Islam, the 12th prophet never died ... he just "vanished" ... and so the Ayatullah wants to make a public announcement to the world that he is the 12th imam who has been wandering the earth waiting for just the right time to reveal himself ... without having to explain how he lost his Arabic-speaking proficiency.
Enter the one HUGE problem. The 12th imam cannot so reveal himself until ... wait for it ... until Israel is destroyed. So the only thing holding up the Ayatullah's prohethood is Israel. Now the Ayatullah doesn't actually need to destroy all of Israel. If he can just get some really big bombs to explode in Jerusalem and Tel Aviv, and capture some massive smoke on video, he can claim that Israel has been destroyed and claim victory. This is why the rockets from Hezbollah and Hamas NEVER end. They figure that maybe if they can COMPILE enough footage of Israel's destruction then they can make a plausible claim that Israel has been destroyed. Too much is riding on this to allow any angle go untried.
Of course, nothing has been of any avail. It has become readily apparent to the current Ayatullah, as it did to his predecessor, that the only hope is to get a nuke into Israel. Poison gas won't work because killing lots of Israelis won't accomplish what is needed. They need visual evidence to support the claim that "Israel has been DESTROYED" that will be believable to Muslims around the world.
Iran will stop at nothing to get a nuke into Israel. There can be no reasoning with Iran on this matter.