Washington — Events here and in California this week point to the growing importance of defending against ballistic-missile attack. Many defense analysts say that such an ability could do more to deter nuclear war than could the new strategic weapons being developed by the Soviet Union and the United States.
President Reagan will receive reports from his top national security officials that outline how the US could deploy advanced systems - including lasers based in space - to destroy enemy missile warheads. These reports, from two panels of experts, will urge that as much as $27 billion be spent over the next five years to explore and develop these possibilities.
This follows the President's controversial ''Star Wars'' speech of seven months ago, in which he called on scientists ''to give us the means of rendering these nuclear weapons impotent and obsolete.'' Mr. Reagan is expected to talk about new potential for space in a speech at the National Air and Space Museum today, and is sure to be questioned about it at his scheduled press conference this evening.
At the same time, Soviet interest in strategic defensive capabilities was highlighted this week with the arrest of an American engineer in California charged with selling to Polish intelligence agents details about how well Minuteman intercontinental ballistic missiles could withstand a first strike. US officials call the information ''extremely sensitive.''
Such data could help Moscow assess the likelihood of success in launching a first strike. But it also may be part of a Soviet effort to increase its own strategic defensive capabilities. Since three-fourths of its strategic weapons are on relatively vulnerable land-based missiles, the Soviet Union has been doing much to protect these assets against attack. This includes the hardening of missile silos and a strong interest in preventing attacking missiles from reaching their targets.
Conservatives have been urging the administration to publicize US intelligence information showing that the Soviet Union is building a massive ABM (antiballistic missile) system, perhaps in violation of arms control treaties.
The issues are becoming highly political, as shown by the forming of a new political-action committee. The American Space Frontiers Committee recently announced that it will ''raise and spend $1 million for candidates who endorse a space-based missile defense system.''
This new PAC is headed by former Defense Intelligence Agency chief Daniel Graham and backed by a group of conservative members of Congress and retired military officers. General Graham, a retired Army lieutenant general, says the US could deploy a relatively cheap nonnuclear missile defense system, and that it could be done quickly.
Many experts - including most Pentagon officials - are skeptical of such claims and urge a more moderate course. The White House seems to be taking one. Reagan has called it ''a formidable technical task'' that ''will take years, probably decades, of effort on many fronts.''
Yet he does want to move ahead on what he has called ''our ultimate goal of eliminating the threat posed by strategic nuclear missiles.'' And the new reports, as well as the expected increase in Pentagon spending in this area, represent the first steps toward achieving a goal some have likened to President Kennedy's call to put a man on the moon within 10 years.
''Ultimately, of course, we hope the United States and the Soviet Union could find that defensive capabilities can enhance our mutual security and could then enter into a more comprehensive arms control treaty,'' White House spokesman Larry Speakes said Tuesday. He denied charges that a missile defense system would necessarily violate provisions of the 1972 ABM treaty.
Critics fear that it would be impossible to create a protective umbrella that would not let some warheads through. Some feel that trying to perfect such a system could lead an opponent that feels less protected to launch a preemptive attack.
It has been suggested that the US might want to share such technology with Moscow if it proved effective. While the Soviet Union (until now, at least) has been directing greater effort toward antiballistic systems, the US has made some advances, too. The Air Force announced in July that it had successfully tested an airborne laser against a missile traveling at nearly 2,000 miles an hour.
As outlined in the current issue of the authoritative journal Aviation Week & Space Technology, the proposals to the President include researching three types of lasers. Other recommendations include using high-altitude aircraft and infrared sensors to detect and track reentry vehicles (warheads) from missiles. Beginning such a program is estimated to cost from $1.8 billion to $2.7 billion next year. Fashioning a multilayered defense system by the end of the century could cost as much as $95 billion, the magazine reported.