As Israel enters its 61st year, Israelis may look back with pride. Yet, the realists among them must also look forward with foreboding.

Israel is a modern democracy with the highest standard of living in the Middle East. In the high-tech industries of the future, she is in the first rank. From a nation of fewer than a million in 1948, Israel's population has grown to 7 million. In seven wars -- the 1948 War of Independence, the Sinai invasion of 1956, the Six-Day War of 1967, the Yom Kippur War of 1973, and the Lebanon wars of 1982 and 2006 -- Israel has prevailed, though some of these wars were, as Wellington said of Waterloo, "a damn near-run thing."

Israel has revived Hebrew, created a new currency, immersed her children in the history, ancient and modern, of her people, and established a homeland for Jews from all over the world, millions of whom have migrated there to settle. Israel is now home to the largest concentration of Jews anywhere on earth.

Here, however, we come to the heart of the existential crisis.

Israel became home to the largest Jewish population on earth in part because American Jews in the 1990s fell in number from 5.5 million to 5.2 million, a loss of 300,000, or 6 percent of the U.S. Jewish population.

According to Charles Krauthammer, by 2050, the U.S. Jewish population will have shrunk another 50 percent to 2.5 million. American Jews are slowly vanishing. How and why is this happening?

It is the collective decision of American Jews themselves, who have led the battles for birth control and a woman's right to choose.

As Jews were roughly 2 percent of the U.S. population from Roe v. Wade to today, perhaps 2 percent of the 50 million legal abortions since Roe were likely performed on Jewish girls or women, resulting in 1 million lost members of the Jewish community in 35 years.

And if demography is destiny, Israel's future, too, appears grim.

As former Ambassador Zalman Shoval writes, Israel's population of 7 million is 80 percent Jewish. But the Palestinian population of Israel has risen to 20 percent and is growing much faster.

One Israel blogger, using Shoval's totals, writes that among the Israeli population between 1 and 4 years old, roughly 30 percent is Arab. The future of Israel is thus increasingly Arab and less Jewish.

According to the United Nations, by 2050, Israel will have 10 million people.

By then, the Arab population, at present birth rates, is likely to be close to 30 percent of the Israeli population. On the West Bank and Gaza, today's 4 million Arabs are to explode to 10 million, far outstripping the growth in Israel. Jordan's population of 5 million, 60 percent Palestinian, will also double to 10 million.

Thus, not even counting Palestinians in Lebanon, Egypt, Saudi Arabia, Syria and the Gulf states, Israel's 7 million to 8 million Jews in 2050 will be living with 13 million Palestinians in Israel, Jerusalem, Gaza and the West Bank. If Israel is to survive as a Jewish state, a separate and independent Palestinian state would seem an imperative.

Yet, as Israelis continue to build outposts and expand and add settlements, the possibility of a Palestinian state recedes. Indeed, many Israelis, seeing what an end to the occupation produced in Gaza, refuse to consider any pullout at all from the West Bank.

Such a policy of holding on and digging in is sometimes the best one -- but only if time is on one's side. Is time on Israel's side?

According to the world population statistics from the National Policy Institute, the worldwide Arabic population in 1950 was only 94 million, less than 4 percent of the world population. But by 2050, it will be 700 million, 7 percent of a world population of almost 10 billion.

According to U.N. population experts, Lebanon's population will grow to 5 million in 2050, but Syria's will almost double from today's 20 million to 34 million. The population of Saudi Arabia will rise from 24 million to 45 million. Egypt will grow by more than 50 million to 121 million Egyptians by 2050. The Islamic Republic of Iran, 71 million today, is expected to reach 100 million at mid-century.

And, demography aside, the Islamic faith of Israel's neighbors is becoming militant. Hamas now controls Gaza. Hezbollah now controls Southern Lebanon and is becoming the power in Beirut. While Egypt is headed by a pro-American autocrat, the principal rival for power is the widely popular Muslim Brotherhood.

Those who do not like the Saudi monarchy should consider what is likely to rise in its place, should the House of Saud fall. The same is true of the Jordanian and Moroccan monarchies, and the sheikdoms, emirates and sultanates of the Persian Gulf.

In any struggle of generations, the critical question is often: Whose side is time on? As President Bush celebrates Israel's 60th birthday, and is celebrated in turn as Israel's best friend ever, it is a fair question to ask.