If Egypt, Jordan, or Syria invades, the IDF is well prepared to handle the situation. The IDF lacks the ability to invade and conquer Iran. In fact, the IDF has proven incapable of occupying Lebanon, or crushing Hamas or Hisbollah. It is still, quite capable of turning back any conventional invasion of Israel.
Police arrest 18-year-old Palestinian suspected in Old City stabbing (Haaretz)
from the article: Here's why Israel must not attack Iran now