West German Chancellor Helmut Kohl visits Washington this week at a time of particular challenge and opportunity for the Western alliance.
With the lifting of US-imposed sanctions on the Soviet gas pipeline, the release of Lech Walesa, and softened American rhetoric attending the death of Leonid Brezhnev, East-West tensions have relaxed a bit, at least symbolically. European allies, who continue to be more interested in detente than the Reagan administration, find this comforting.
At the same time the new German leader, although more philosophically aligned with the White House than his predecessor, Helmut Schmidt, faces serious economic and political uncertainties at home. Thus, Dr. Kohl is unable to deliver all that the Americans would like, particularly in helping strengthen the allied military presence in Central Europe.
The new conservative government in Bonn (in the German chancellor's words) wants to ''dispel the doubts that have fallen on German-American relations . . . by reaffirming and stabilizing our friendship.''
Since his election six weeks ago, he has reaffirmed West German support for the Reagan administration's nuclear arms control proposals, as well as the NATO plan to deploy Pershing II and cruise missiles a year from now if arms talks fail.
The Kohl government also has left intact the defense portion of a federal budget that otherwise is being cut to reduce government deficits and promote economic recovery.
At the same time, the Federal Republic of Germany faces what Chancellor Kohl calls ''the most challenging economic situation since the end of the war.'' This means West Germany will not be able to increase defense spending to the extent outlined by NATO.
Two security issues are of particular importance. The Pershing missile failed its first two tests and the third test was canceled late last week. If deployment is delayed, even for technical reasons, German officials fear this will add to the growing antinuclear sentiment in their country and perhaps fatally undermine the NATO ''two-track decision.''
Related to this is German concern over the controversial MX strategic nuclear missile and whether in fact this new weapon will ever be deployed in the US. There is growing opposition in Congress to the MX.
''People then should say, if the Americans do not want to position missiles on their soil, why should we position them on our soil,'' West German Defense Minister Manfred Woerner told American reporters.
Also of concern, and a subject of discussion between Messrs. Reagan and Kohl this week, is the move in Congress to reduce US troop strength in Europe. Such a pullback, said a senior German official, ''would be a major success for the Soviet Union . . . a major contribution to decoupling.''
It is this separation of the US from its European allies, that the meeting here between Kohl and Reagan is designed to prevent. Thus, American concerns about technology transfer and trade credits to the Soviet Union (as outlined in the face-saving pipeline sanctions resolution) are being stressed as well.
Politically, their meeting here is a boost for both leaders. On the heels of the pipeline controversy and the recent exchange of saber-rattling between the US and the USSR, Reagan finds it supportive to have a prominent, friendly European face in Washington.
Kohl's visit follows successful talks with Margaret Thatcher and Francois Mitterrand that have helped establish his national leadership. He faces a federal election in March, on which hangs his political future.