It appears that the Carter administration has misjudged the likely reactions to the proposed nomination of Lt. Gen. George Seignious as director of the Arms Control and Disarmament Agency. Seignious' selection, insiders say, rested on the assumptions that a well-regarded military officer could avoid a confirmation fight and win Senate ratification of a SALT treaty in 1979. Both assumptions are flawed. Far from being a safe appointment congenial to all quarters, the nomination of this retired solider poses problems for both the left and the right. The problems are institutional and political and not a question of his personal qualities.

The distinctive history and mission of the arms-control agency raise doubts about the wisdom of appointing a career military man to head it. A principal legacy of Hubert Humphrey, the agency was conceived and created for the precise purpose of developing non-military approaches to the nation's security interests. Its premise was that there should be at least one institution in the U.S. government charged with enhancing security through negotiated arms restraint, rather than through exclusive reliance on military means. This emphasis was not anti-military; the idea was to supplement and, if possible, reduce the burdens on the military establishment by vesting the task of arms diplomacy in an independent agency.

From the beginning, military professionals have made important contributions to ACDA's work. Officers of flag rank have regularly served as assistant director for weapons evaluation and have played a crucial role in liaison with the military departments. They have done so, however, under the direction of civilian leaders of ACDA. The Seignious appointment breaks that precedent, and a number of groups are pressing a law for ACDA like the one that prohibits appointment of a retired military officer as secretary of defense.

To be sure, the issue of civilian control of ACDA is not identical to that in the Defense Department. The ACDA director does not command an army and the office is a frail mount indeed for any would-be man on horseback. Yet there is a persuasive analogy: If war is too important to be left to generals, the vital issues of arms diplomacy also require a direction that decisively subordinates the institutional claims, ambitions and psychology of the military services. No matter how conscientious he may be, a career military professional cannot be expected to abandon the attitudes and orientation acquired in a lifetime of service in the craft of arms. To draw ACDA's leadership from this source is to jeopardize its independence, not through deliberate usurpation, but through more subtle processes. Having shared decades of military companionship, a general officer may well take his cues from his uniformed associates, drawing many of his insights and intellectual reinforcements from those with whom he has served. In dollars, manpower and access to the policymaking process, senior military figures already enjoy predominance in the national-security field. Is it really wise to station a military leader at the head of the one agency specifically designed to bring broader views to bear on the country's weapons-acquisition and arms-control plans?

That the problem is a real one is confirmed by Seignious' first personnel decision at ACDA. With insensitivity, he has immediately replaced a civilian with another retired military officer as executive secretary of the agency. It is also suggested by his curious explanation of his involvement with the Coalition for Peace Through Strength in the months prior to his ACDA appointment. He signed on to the coalition, he says, not because he concurred in its opposition to SALT, but because he was "honored to be associated with" other members, such as Adm. Thomas Moorer and Gen. Lyman Lemnitzer. Loyalty is a commendable quality, but in this case, Seignious' old service ties do not augur well. There is more than a plausible risk of conflict of interest between the general's familiar connections and the novel organization he now guides. On these grounds, a conservative respect for procedure, no less than a liberal attachment to the agency, argues against the appointment.

These institutional concerns gain added force when one takes account of the fact that the Central Intelligence Agency is already directed by a military officer. One recalls the long-simmering anxiety of American analysts during the period when Marshal Andrei Grechko served as Soviet minister of defense. The appearance of growing military dominance of U.S. foreign-policy machinery may breed similar suspicion and apprehension abroad, all the more because we have so long professed civilian supremacy.

Beyond those considerations of principle, the Seignious nomination is a serious political miscalculation. The ploy offends the very people it was meant to entice, particularly those skeptical of the present course of SALT negotiations. As one member of the Committee on the Present Danger scoffed, "Does the administration really believe we will support SALT because they've got a guy at ACDA with a star on his shoulder?" The committee's most prominent figure, Paul Nitze, says that he was "neither consulted about nor satisfied with the Seignious appointment" -- despite reports that the move was intended to placate him and his associates. In truth, Nitze endorsed Ambassador Ralph Earle for the post.

The ploy proved counterproductive partly because it is known that other generals, notably former NATO Commander Andrew Goodpaster, had declined the post. The administration left the clear impression that it confined the search to military candidates as a sop to SALT critics. While that might have worked with a person of Goodpaster's eminence, it emerged finally as mere expediency.

Whatever potential the idea had for pacifying the right, it dissolved in the uproar over Seignious' abrupt resignation in October from the American Security Council and the Coalition for Peace Through Strength. In those circles, he is now viewed as a "turncoat general," less trustworthy than a civilian.Laying the groundwork to oppose the nomination, the coalition (whose co-chairmen are Sens. Robert Dole of Kansas, J. Bennett Johnston Jr. of Louisiana and Paul Laxalt of Nevada) is circulating its correspondence with Seignious. It includes the letter of resignation for which he has since apologized, saying it should have been "more temperate." The episode earns him no support with such affiliated groups as the American Conservative Union and Young Americans for Freedom.

Obviously worried at these developments, the administration has given Seignious a recess appointment under which he might serve up to one year without Senate confirmation. This only compounds the original error, for many senators will resent the apparent effort to preempt opposition in the confirmation process. Some Republicans who might otherwise favor a greater military role at ACDA grumble about Seignious as "a general who salutes with both hands." They assume that he will do as he is told and be little more than a figurehead. One adviser to a Senate leader describes the whole affair as a plot by Paul Warnke to trick Zbigniew Brzezinski into foisting off a dove in soldier's clothing.

For a nomination of such delicacy, the preparation for it was extremely thin in the Senate. Assuming that the move would please ACDA's critics, the administration took it for granted that the agency's patrons would have no choice but to stomach the change. SALT sympathizers are being asked to suppress their discomfort over the nomination, lest a confirmation battle further prejudice prospects for treaty ratification. But as it becomes evident that the general may be more a liability than an asset in courting votes among uncommitted or reluctant senators, tolerance for the nomination could decline on both flanks.

Thus, the Seignious nomination provokes the squabble it was designed to avoid. The irony must be painful to Seignious, who is undoubtedly a dedicated public servant. Instead of smoothing the way for victory in SALT, his presence at ACDA may trigger a fractious dispute. The constructive and courageous course would be for him to urge the president to find someone else for the job.