Standing atop a windswept, rocky hill that in two years has been transformed from barrenness to a burgeoning new Jewish town named for him, Ariel Sharon squints at the haze-shrouded Mediterranean coastline with a map clutched in his hand, looking and talking more like the Army general he once was than the agriculture minister he is.

"Every settlement is part of a territorial defense system that is crucial to the existence of the state of Israel. One cannot support the concept of a place like Ariel and be for territorial compromise," Sharon says.

Historical rights and political considerations aside, a fundamental argument for settlements has always been national security. But whether by chance or design, security has become so entangled with biblical prophecy that it has almost been lost.

Shortly after Israel captured the West Bank in the 1967 war, the then-incumbent Labor Party government emphasized security as it built a chain of heavily fortified settlements along the Jordan Valley, blocking five strategic passes and valleys through which an invading Arab army would have to travel to reach Israel.

In those days, mystical arguments based on biblical rights were overshadowed by what seemed to be clear, realistic military logic, even if Jordan and other Arab states were having none of it. The logic, no doubt, reflected the political bent of the Labor Party's brand of practical Zionism, as opposed to the mysticism of the revisionist Zionist movement of Zeev Jabtmsky and Menachem Begin.

When Begin came to power in 1977, the military justification for settlements all but disappeared from the rhetoric of Israel's new rightist leaders, and the transfer of a Jewish population to an occupied area was presented to the world as Israel's God-given right to all of biblical Eretz Israel (the Land of Israel) from the Mediterranean to the Jordan River.

But mounting international opposition to Israel's settlement policy, and particularly the rise of doubts in the American Jewish community, appears to have shocked the Begin government into reverting to the old security arguments and toning down the historical ones.

The arguments are based partly on the terrain of the West Bank and partly on the closeness of large Arab populations to densely populated areas of Israel proper.

Sharon noted that about 60 percent of Israel's population lives in a narrow strip of coastal plain ranging from six to 15 miles wide, and that 150,000 Arabs live along both sides of the pre-1967 border -- Israeli Arabs on the west side and West Bank Arabs on the east side.

Because of this lack of depth along the coastal plain, Sharon maintained, it is necessary for Israel to settle Jews in a line of communities along the ridges overlooking the plains so that they can act as a buffer against an Arab attack that could cut Israel in two at its narrow waist.

One dramatic illustration of the closeness of the West Bank to Israel is the Jerusalem-to-Tel Aviv highway, which crosses the pre-1967 border four times, almost certainly by design since the highway was built in 1978.

Similarly, the line of settlements on a mountainous spine overlooking the Jordan Valley, and the settlements on the valley floor itself, serve as a buffer and early warning against attack from Jordan, Sharon said.

The third major defensive deployment, Sharon said, is a ring of highrise Jewish satellite towns being built around Jerusalem and ultimately intended to house 300,000 Israelis, nearly the population of Jerusalem today. iThe Jerusalem defensive circle includes the settlements of Gilo, Gush Etzion, Efrat, Maaleh Adumim, Ofra, Beit El and Givon.

All three deployments, Sharon said, are intended to slow down an enemy attack long enough to bring up reinforcements. With a relatively small standing Army Israel is reliant on a rapid call-up and mobilization.

"We've tried it in wars and the settlements showed they could hold on until the main troops move up. We tried it in 1948 and 1967 and 1973. They [the settlers] are highly motivated, they know the terrain and their strength is higher than their numbers," Sharon said. He added, "These people have guns, and they know why they are here."

But persistent questions have been raised in Israel about the validity of the security value that has been attached to settlements. Just minutes after the outbreak of 1973, the Army command ordered the evacuation of front-line settlements on the occupied Golan Heights, fearing they would be overrun by Syrian troops.

Sharon calls that decision "a mistake." But nonetheless the 1973 experience has convinced many Israelis that vulnerable settlements can serve merely as easy front-line support posts for an invading army.

Moreover, settlement critics contend that it takes longer for the Army to mobilize and that lightly armed settlers could never hold off a concentrated attack that long. Worse still, the critics contend that the Israeli Army's strength would be diluted because of the need to rush to 72 settlements in the West Bank alone to rescue besieged settlers.

This argument was advanced last November by two prominent former generals -- Mattiyahu Peled and former chief of staff Haim Bar-Lev -- who, in written testimony in the controversial Elon Moreh land seizure case before the Supreme Court, warned that settlements could actually hamper the smooth deployment of army troops to meet an Arab frontal attack.

Another drawback is that, currently, about 80 percent of the West Bank's working settlers commute to somewhere else -- often to Tel Aviv -- to their jobs, leaving the settlements inhabited during the day mostly by women and children.

Sharon dismissed that argument, saying the decision had been made long ago to build "skeleton" settlements first and then later add factories and businesses that will keep the men near home.

"When the time comes, they will get back in time," Sharon said. "These people will defend themselves. They will keep the roads open."

Beyond the historical right and security justifications for settlements, there is another argument. It is constantly cited by Israel's Arab neighbors and even by Israeli critics of settlements, but only rarely mentioned by advocates of Begin's policies in the West Bank.

It is the justification of making a negotiated Israeli withdrawal from the West Bank or even a territorial compromise an impossibility by establishing facts on the ground.

If hundreds of thousands of Israelis are living in permanent, massively constructed apartment buildings that blanket every quadrant of the West Bank, it is reasoned, how could Israel ever be expected to withdraw from the territory it holds to be rightfully its anyway?

If you mix a Jewish population with an Arab population in the West Bank, thereby "cooking an omelette," as ultranationalist settlers often say, how can you possibly unscramble the omelette?

If, five years from now, as is expected, 10,000 Israelis are living on once-Arab land in a sprawling highrise apartment complex at Maaleh Adumim, what international entreaties are going to relocate 10,000 persons and bulldoze a multimillion-dollar housing investment?

In the three decades before the holocaust-ravaged Jewish nation won a homeland in 1948, settlements played a major role in the creation of the state, first to compel the United Nations to partition Palestine and then to draw the demographic lines between the Jewish and Arab populations -- a line that almost precisely followed the lines of settlement.

It is this strategy, according to the Palestinians of the West Bank and leaders of surrounding Arab states, that Israel is following more than the strategy of biblical rights or the strategy of military security.