Will the Social Democrats now slide from rejection of new NATO missiles into anti-Americanism and aloofness from the whole alliance? This is the issue West Germany is beginning to probe with the two-day missile debate in parliament that started Monday. It was the focus of Chancellor Helmut Kohl's opening statement and - from a very different perspective - the Greens' riposte by Otto Schily.
It was conspicuously not the focus of Social Democratic leader Hans-Jochen Vogel, however.
This dichotomy bespeaks a certain surrealism that is highly unusual for the outspoken Germans. Almost all Social Democrats in parliament think their party will never put NATO and the American alliance at risk. Almost all Western diplomats think the contrary.
In his keynote speech, Chancellor Kohl warned the Bundestag repeatedly of this danger. ''The orientation of our country stands at risk,'' he said bluntly. He was speaking not about the several thousand antinuclear protesters who were demonstrating outside the Bundestag or the 150 who were being detained for breaching the parliament's ''no demonstration'' zone. He was speaking instead about the main opposition party, which a few days ago rejected the imminent deployment of new NATO missiles that was planned under Social Democratic Chancellor Helmut Schmidt.
The Social Democrats' ''no'' vote today will not block the deployment due to begin next month. Dr. Kohl has a secure center-right majority to approve the missiles. The Social Democrats' shift will, however, polarize this key country for the NATO alliance and for the deployment.
In pressing his charge of inconsistency by the Social Democrats, Kohl argued that West Germany can fulfill its mission of peace and freedom only in the context of its Western alliance. ''We are not wanderers between two worlds'' of East and West, he asserted in a favorite phrase. With the help of the alliance, the West must now have the political will to show Moscow that the Soviet missile buildup of recent years will not go unanswered.
This is precisely what the Social Democrats are not prepared to accept. For Kohl this unwillingness threatens alliance solidarity and the coupling of Europe with the US, and even isolates the West German Social Democrats from fellow French and Italian Socialist parties, which support the NATO deployment.
Mr. Vogel hardly saw the issue in such stark terms. For him it was still an issue of policy only, not one of loyalty to the alliance. He warned Kohl not to fall into the trap of thinking that whoever opposes the stationing also opposes the alliance and West Germany's own armed forces. He said his party's purpose in rejecting the deployments was rather to break the arms spiral and allow time to probe seriously Soviet moves toward compromise.
For the antinuclear Green party, the issue is, in fact, West German membership in NATO and subservience to the United States. The Greens want to pull out of the alliance. They deride the Social Democrats for belatedly jumping onto their bandwagon in opposing the missile deployments without also opposing the whole bloc. Mr. Schily called instead for neutralization of Central Europe (including Germany) between East and West.
Within the Social Democratic Party (SPD), only one prominent voice - that of Saarland Party leader Oskar Lafontaine - calls for West German withdrawal from NATO. And the resolution at the party convention Saturday expressly approved NATO.
For this reason the SPD pragmatists contend that the danger of a Social Democratic slide away from NATO has been averted. They say the fierce internal party arguments over the past months have clarified the continuing SPD commitment to the alliance and to partnership with the US.
NATO diplomats here do not share this conviction. They believe the emotional momentum of antimissile sentiment in a party without the discipline of power will press the SPD to distance itself more and more from the US - and to a lesser extent from NATO. They regard as indicative the mood at the SPD convention, where outraged references to El Salvador and Grenada roused much more reaction than a perfunctory mention of Afghanistan.
NATO diplomats expect the only thing that will eventually pull the SPD back from this course will be the reality of elections. With luck, they say, the Social Democratic return to the mainstream defense policy will come with the North Rhine-Westphalia state election next year. In this Ruhr workers' heartland , the SPD lost 6 percent of its core voters in last March's general election as the party began its leftward swing.
If no change is effected by then, the diplomats suggest, any Social Democrats who want to regain power will have to change their party's course by the time the conservatives have held the chancellery for two terms. That will be in the early 1990s.