Despite some remarkable political success in the early going, the Reagan administration is showing a glint of that pale cast of frustration that all governments acquire. Most of the larger vexations are connected. First, in defense spending the early reach of Reagan and his advisers somewhat exceeded their grasp. Second, in searching for a way to deploy the MX, which they regard highly, the Reagan people, like many before them, haven't discovered a way of hiding missile systems on land that doesn't create more problems than it is supposed to solve; the alternatives of deploying the MX in airplanes or as a supplement to current and planned sea-based forces look to be no more promising. Next and most serious, our European allies may put some distance between their security policies and those of the administration, which are widely seen in Europe as anachronistic and probably dangerous.

Anachronistic is not a bad way to describe Reagan's uncomplicated hard line. It recalls the simpler era of the cold war when confrontation, as in Berlin, was a constant and immediate threat. Reagan's security policy, in the main, arises from assumptions that, until recently, were well outside the mainstream. They displaced others that by and large governed the policies of the Kennedy, Johnson, Nixon and Carter administrations. They also governed Gerald Ford's until early 1976, when he began competing against Ronald Reagan for the support of their party's right wing.

The displaced and, I suggest, more orthodox assumptions began to form in the period following the end of the Cuban missile crisis, an episode that took Berlin off the boil and led to the first significant arms control agreement, the limited test ban treaty. It became increasingly clear that an era of parity, or equivalence, in nuclear weapons had begun. The time when either side would allow the other to acquire an exploitable strategic advantage over the other was fast fading. There developed a basic, if tacit, assumption that America had the potentially conflicting tasks of maintaining the cohesion of the North Atlantic security system and assuring some degree of stability in East-West relations. The SALT process became striking proof that any conflict between these twin requirements was more apparent than real. In time, Europeans acquired an unshakeable opinion that their stake in SALT was at least as great as our own. They share our interest in reducing the risk of nuclear war, whether by accident, design or miscalculation. And while obliged by the threat from the East to maintain substantial military forces, they also have the need for some stability in their relations with the Soviets. They see SALT as the agent of stability.

It is ironic that as the link between security and arms control became as clear to European governments as it had been to succeeding American presidents, there arrived in Washington a politically well-established administration that in most of its parts rejects orthodox thinking on these matters. The SALT-related goals of limits based on parity and equivalence were set aside in favor of developing "margins of safety" that are supposed to restore some measure of superiority.

Reagan has a choice that is a lot more complicated and of greater importance to his political fortunes than he probably thought it would be. He can continue to reject the more orthodox views of predecessors and allies. Or he can make virtue of what some would judge eventual necessity by restoring orthodoxy. He and his people could, for example, treat SALT for what it is, or should be--a major element of security policy, a process that will work only if invested with confidence and priority importance. This alternative could be used by Reagan to contain, perhaps dissolve, some of his more pressing difficulties. A major dust-up in the alliance--an alarming prospect--would be avoided. Reagan would acquire more flexibility in dealing with the MX problem, especially if he should wish to lighten his commitment to it now that the famous threat to land- based missiles is at last beginning to be considered more realistically. Reagan might also ponder the merit of being able to trade a sensible and limited MX deployment for a Soviet move of at least comparable strategic importance in SALT. A decision not to deploy it at all would doubtless fetch that much larger a return. The public discussion of the MX (and ICBM vulnerability) will not diminish its bargaining value any more than the debate on ballistic missile defense depreciated the ABM's bargaining value during the SALT I negotiations.

A restoration of SALT, with a commitment to serious bargaining, would clearly help Reagan with the defense budget. The more obvious and urgent military needs lie well outside the area of strategic weapons; they involve conventional weapons, an area where NATO's chief advantage over the Soviet Union (apart from the doubtful reliability of Soviet allies) is technological and can be maintained only through continuing improvement. This requirement, like having an adequate supply of adequately trained manpower, is very expensive.

What, it may be asked, of the constraints on Reagan that could discourage a revival of orthodoxy? Probably, he and those closest to him will not let them selves be diverted, not significantly, from the path that has always seemed right to them. Still, it is just conceivable that the experience of the past few months, plus the harsher times that doubtless lie ahead, will lead this politically astute president to a more temperate view of security matters. If so, he is more than strong enough within his own most reliable constituency to change course. Indeed, not since Richard Nixon's first term, when he journeyed to China and concluded the SALT I agreements, has any president's writ in East-West matters run as far as Reagan's would appear to now. Neither Gerald Ford nor Jimmy Carter felt free to push a SALT II agreement through to ratification, let alone decide that ICBMs are not actually vulnerable after all.

If, as seems likely, Reagan keeps faith with his deeply felt concerns, he is likely to invite very considerable difficulties all along the line; his political position will eventually be harmed. Changing course, however, would offer him a sure claim to the role of protector of stability and undoubted leader of the Western alliance. In such a role, he stands a chance of anchoring his large political base.