What is the most direct legal action I can take to get my children back home to the States after my wife ran off to Israel with them-where her parents live- while I was at work and refuses to return?

File fast-track Hague Convention civil child abduction proceedings against your wife at the family court in Israel, for the "prompt return" of the children to the U.S.A, presuming that the States is their country of habitual residence, and they were removed from Israel without your knowledge and consent, as indicated by you.