As Washington arises from its -August torpor, arms control is once again becoming a dominant topic of concern. The latest Soviet offer on intermediate-range nuclear missiles in Europe puts the negotiating ball back into the American court, apparently answering one key Western concern while highlighting several others. On strategic nuclear weapons, the Reagan administration has shown some recent flexibility and has attempted to demonstrate its earnestness by beefing up the Arms Control and Disarmament Agency.
On Capitol Hill, however, there are, as one lawmaker puts it, ''raised eyebrows of suspicion'' over the administration's credibility on arms control. Many congressional arms control advocates say the administration is slighting the arms control part of the Scowcroft commission's triad of recommendations on the strategic balance (deploying some MX missiles and developing a new, smaller mobile missile are the other two).
''People are wary of being snookered,'' says Rep. Les Aspin (D) of Wisconsin, a member of the House Armed Services Committee and congressional expert on the subject.
At the same time, Mr. Aspin, a liberal who sees the logic of the total Scowcroft weapons and arms control package, says he also sees the political debate hardening into an ''arms control Tong war'' that must be replaced by domestic political compromise before any agreement with the Soviet Union is possible.
Sen. William Cohen of Maine, a moderate Republican and author of the ''build down'' concept (scrapping more older missiles than new ones deployed), has threatened to abandon the administration on the MX if arms control progress is not seen soon. This could lead others to follow suit when the MX, for which congressional support is tentative at best, comes up for appropriations votes later this fall. Anti-MX activists have been very busy during the congressional summer vacation just ending.
Congressman Aspin this week urged retired Air Force Lt. Gen. Brent Scowcroft and his panel of experts to ''move into high gear for the specific purpose of helping to frame an arms control position.''
The Scowcroft Commission has been kept intact, but assumed a less active advisory role since issuing its report to President Reagan last April. Advocates of its recommendations for stabilizing the superpowers' strategic arsenals believe it must continue its bipartisan work in a more visible way if major stumbling blocks are to be overcome. Among the controversial issues still to be resolved among US arms control partisans are the numbers of allowable large, multi-warhead missiles, their throw weight (the total weight of a missile's warheads and their targeting devices), and the number of allowable strategic bombers.
''The key question in strategic arms control today is whether we can get beyond negotiating among ourselves so that we can begin to negotiate with the Soviet Union,'' says Aspin.
On theater nuclear weapons, negotiations between the United States and the Soviet Union resume next week in Geneva. Soviet President Yuri Andropov took the public debate one step further last week by offering to dismantle some SS-20 rockets now aimed at Western European countries rather than simply moving them.
This leaves at least two key allied concerns: Soviet insistence that British and French nuclear forces be counted in the negotiation mix (and that therefore no new US-built Pershing II and cruise missiles be deployed as scheduled in December); and the Soviet SS-20s based in Asia that threaten Western allies there or could be moved into Europe.
Beyond these difficulties is the aim of both sides to head off deployment of new generations of nuclear weapons to be based in the European theater. The Soviets already have begun to modernize their shorter-range nuclear missiles with SS-21, SS-22, and SS-23 rockets, which may be deployed in Warsaw Pact countries not far from Western forces.
Britain and France plan to replace their older, single-warhead nuclear missiles, most of which are based on submarines. Britain is buying the multi-warhead and very accurate Trident II missile from the US. France will upgrade its submarine missile force with new multi-warhead weapons as well, and also will acquire new airborne nuclear missiles with a longer range. These moves will increase the number of British and French nuclear warheads - directed presumably at the Soviet Union - by several times.
Arms control advocates see such advances on both sides as an increasing threat to negotiated reductions.