Iran has had its panties in a wad over the air defense radar in particular. They have been complaining to Turkey about it and finally attempted to take it down using terrorists.
From 2011: http://www.israelnationalnews.com/News/News.aspx/151050#.Vhio6JtdFYc
The effort to strike it using terrorists was more recent.
Thanks for the background.
The Patriots could protect this particular missile defense system radar which the Iranians dislike so much and have attempted to take down through proxies because this system acts as an early warning system for Israel as well as NATO.
Thus Iran sees the Patriots as a “threat” to their offensive capability against that particular radar system, and therefor a “threat” to any future strike Iran may want to take against Israel. Israel, meanwhile, for obvious reasons, views Iran’s nuclear program as an unacceptable threat to its existence.
Iran knows Israel has a great need to neutralize the Iranian nuclear program and so far this effort to neutralize it has been deadly serious business, though most people have not been paying attention to just how deadly it has already been.