It’s a foreign policy witticism to say that whenever a crisis occurs in the world the question for some people is always, what does it mean for Israel? With Syria and now Iraq in flames, Israel’s security is not at the top of any country’s agenda other than Israel itself. But Israel’s security should always be a concern for Washington and other governments as well as Jerusalem, both because it’s important in itself and because whatever policy Israel pursues necessarily reverberates throughout the Greater Middle East.

First things first: the Blitzkrieg advance of the jihadist ISIS (the Islamic State of Iraq and Syria) is astonishing. Why was such an invasion, which required extensive planning and gathering of fighters, not scoped out by the intelligence services of several highly equipped countries, including the U.S.? How is it possible that ISIS has taken over several major Iraqi cities with so few fighters, estimated at between three and five thousand? Mosul alone has a population of 1.8 million. How could so few invaders take it so easily, then take Tikrit, threaten Kirkuk and head toward Baghdad? How is it that a major Iraqi defense force collapsed and deserted in the face of a few hundred ISIS attackers?

Whatever the answers to these questions, what this all means for Israel is obviously complicated. Here are only a few of the issues:

1. The civil war in Syria has now spilled over massively into Iraq. Paradoxically, the Syrian internal conflict had increased Israel’s security because the Assad regime and its army were weakened as a possible military threat (including giving up all or most of its chemical weapons capability). The sudden emergence of ISIS as an international force dominating a large territory means that Israel could conceivably end up facing it on the Golan Heights. Israel’s army couldn’t be defeated, but terrorist attacks might develop that would damage Israeli society materially and above all psychologically. Israeli cities would become unsettled, some Israelis might move away from the borders and others might just leave the country.

ISIS, considered as part of the Syrian insurgency, has been fighting against the Assad regime, which is Muslim but divided among Sunnis and Assad’s minority Shia-Alawite sect, and in any case more a fascist thug operation than Islamist. But ISIS also was fighting against other anti-Assad rebel forces, jihadists it considers insufficiently Islamist. Its ostensible goal is to create a new country, an Islamist regime, a caliphate, straddling the eastern Syria/western Iraq border across Sunni areas. Its push toward Baghdad, however, indicates that this goal may be expanding.

2. In terms of the Israeli-Palestinian conflict itself. Along with the diminished threat from Syria to the north, the overthrow in Egypt of the Muslim Brotherhood government last year had increased Israel’s security to the south since the Egyptian army (Mubarak and Sisi both came out of the military) long understood its common interest with Israel in holding down Islamism. Logically, ISIS’s sudden success should strengthen Egyptian solidarity with Israel, as well as with the U.S. and the West in general. On the other hand, ISIS victories are likely to intensify anti-Israel and anti-Semitic attitudes among West Bank and Gaza residents because militant Islam in some general sense seems to be on the march. Thus, ISIS will also give Hamas new prestige as it goes into a unity government with Fatah. The fight inside the future Palestinian Authority government in the coming elections will involve whether Hamas breaks out into the West Bank or Fatah returns in force to Gaza. Whether ISIS or other outside jihadist groups will try to influence the internal Palestinian conflict on the side of Hamas — or the struggle in other countries such as Jordan and Saudi Arabia — is an open question.

3. What Iran will do is a further issue. Superficially, it might seem that the Ayatollah regime and ISIS have much in common: a hard Islamist ideology and anti-Israel, anti-US attitudes. But ISIS and the near-totality of the jihadists world-wide are Sunni and they consider Shia Islam, that is, Iranian Islam, to be infidel. Thus, Tehran is caught between a rock and a hard place and it would be all the more so if Sunni jihadists, ISIS or others, penetrated Iran with terrorist attacks. Conceivably, Tehran will open more to good relations with the West and be more likely than before to make a nuclear deal with the outside powers because the enemy of my enemy is my ally if not my friend.

Faced with all this, what should Israel do? The calculus is becoming more complicated but the strategy is obvious: wait and see. Be evermore on the alert and increase the intensity of intelligence and other operations outside of Israel. Israeli-Palestinian negotiations are on hold for, not months but years. Whether it is more imperative for Israel to make a deal with the Palestinians or more important not to do so is moot. Whether Israel’s interest is somehow to act against ISIS has no obvious answer.

In any case, ISIS has justified an Israeli policy of strength and skeptical diplomacy. Israel lives in a tough, tumultuous neighborhood.