WASHINGTON -- After seven years as the stepchild of the defense establishment and the whipping boy for opponents of the Reagan-era military buildup, the Strategic Defense Initiative is enjoying a rush of good fortune.
The spectacular success of the Patriot anti-missile missile in defending Tel Aviv in Israel and Dhahran in Saudi Arabia has dramatized the viability of ballistic missile defenses. Meanwhile, deep in the South Pacific Jan. 28, an SDI test missile knocked out a mock warhead 100 miles in space -- the first such interception ever.
But perhaps most significant was President Bush's State of the Union announcement that the SDI program would be redirected from its erstwhile -- and widely ridiculed -- goal of providing an impenetrable shield against an all-out missile assault from the Soviet Union to the development of a more limited and less costly defense against accidental launches and limited attacks.
"I'd say things are looking up for SDI," said Representative Jon Kyl, R-Ariz., a prominent champion of the program, commonly called "star wars."
Its opponents, who are legion, had hoped otherwise, complaining that the program had consumed $24 billion without developing the ability to shoot down a single intercontinental ballistic missile, let alone the thousands that a fully operating system is supposed to destroy. Last year, they succeeded in slicing President Bush's $4.5 billion funding request almost in half. This year, they were preparing to pare SDI's budget further.
But events have conspired to blunt those plans, strengthen support for the beleaguered program and, just possibly, win some converts.
"I've been an opponent; I'll take another look at it," said Sen. Howard M. Metzenbaum, D-Ohio.
"There's a shift," conceded Sen. J. Bennett Johnston, D-La. "It certainly changes the mood around here, will change a number of votes."
In fact, SDI's fortunes may be most strongly influenced by the success of the Patriot, a weapon with no formal link to SDI. Although the Patriot was developed by the Army, it draws on many of the same technologies that SDI planners would employ in a more comprehensive missile defense and, SDI's champions say, establishes the desirability of a reliable anti-missile defense.
"I think the proof of the principle is important -- that you can defend against ballistic missiles," said Henry Cooper, who heads the SDI program. "I think the message has been received."
Detractors argue that the Patriot's Persian Gulf task -- shooting down relatively primitive Scud missiles that are a product of 1960s technology -- is a comparatively simple one and that the job facing an SDI system -- destroying multiple-warhead, multi-stage rockets at high altitude -- is a task of exponentially greater difficulty.
"They'll try to make the connection between SDI and Patriot, and it's not going to work," said Sen. Carl Levin, D-Mich. "Different technology, a technology that SDI has not wanted any part of."
Nevertheless, the Patriot system represents a triumph of ballistic and digital technology that did not exist at the beginning of the past decade.
"A spectacular achievement," said Sen. John W. Warner of Virginia, the highest-ranking Republican on the Senate Armed Services Committee. "The recent record is adding tremendous credibility to the whole program."
Adding further credibility, Mr. Warner and his allies say, is a shifting perception of who the enemies of the United States are and against whom a missile defense system is supposed to defend. Ironically, the very trend that threatened to sweep SDI into history's dustbin -- the warming of relations with the Soviet Union -- has now been seized upon by the program's defenders as justification for a renewed and redirected SDI.
It was argued that the threat of massive, catastrophic retaliation was sufficient to keep the two superpowers from launching a nuclear attack against each other.
But SDI's backers contend that the Persian Gulf conflict underscores the dangers of a post-Cold War, multipolar world. Citing Saddam Hussein's drive for nuclear weapons capability, they say that in this emerging world order, poorer countries ruled by despots could acquire the deadliest available tools of destruction. Such countries and such rulers, they continue, would not necessarily be dissuaded from using their weapons by the threat of a commensurate response from the United States.
"The arguments of the past aren't sufficient for all conditions," said Mr. Cooper. "What we've learned here is that relying on retaliation doesn't give you much protection."
"That's the thing that may save it," said Sen. Sam Nunn, D-Ga. "But it doesn't sound that much different than what many of us have been talking about for a long time."
Actually, the administration says that what it has in mind in its new SDI plan, the core of which has been named Global Protection Against Limited Strikes, differs sharply from the limited ballistic defense proposals advanced by many Democrats and Republicans who favor sticking with smaller-scale ground defenses such as the Patriot.
Defense Department officials do say they plan to deploy advanced Patriot-type missiles on ships and at ground locations by the mid-1990s, at a total cost, they say, of about $9 billion.
Beyond that, however, they envision a network of up to 1,000 interceptors based in the United States that would attempt to destroy incoming missiles as they homed in on their targets; another network of 1,000 satellites, dubbed "brilliant pebbles" and armed with sensors, computer circuits and an interceptor that would strike missiles soon after their launch; and 80 satellites, "brilliant eyes," that would track missiles, deployed warheads and decoys.
The total cost is billed at nearly $40 billion.