"Reagan has made a mistake." This was the private assessment one senior Soviet official made Aug. 11 of the US decision to go ahead with production of neutron weapons.
Even as he spoke, the Soviet Union was gearing up for a media campaign to encourage uneasiness over the US move among America's West European allies.
The strategy is not new. It has scored at least limited success since Mr. Reagan moved into the White House barely six months ago.
But Western diplomats here had little doubt that the neutron bomb decision would give the Soviet drive fresh impetus.
Before Mr. Reagan's move on the neutron warhead, Soviet eyes, pens, and typewriters had been trained largely on US plans to base new nuclear missiles in Western Europe.
Moscow took a carrot-and-stick approach, dangling various "peace initia tives" before the West Europeans, while reminding them that nations like West Germany would surely become key battlefields in any superpower war.
The immediate effect -- although its extent is impossible to gauge -- was to help bolster pro-detente and antinuclear forces in Western Europe.
They have almost certainly been a factor in pressure from West European nations for early arms talks with Moscow.
While presumably pondering whether to act on public hints that they will produce their own neutron weapon, the Soviets are moving quickly to encourage West European concern over the US decision on the warhead.
The official Soviet news agency, Tass, has been highlighting what it terms a worldwide "wave of indignation" over the move, welcoming opposition to the US decision in Sweden and Norway, and throwing in reaction from more far-flung parties (Mozambique, for example) for good measure.
Soviet commentators are also, pointedly, wondering out loud why NATO states like West Germany and Britain have not joined the crowd.
"The great danger of the neutron weapon for the peoples of European countries is obvious," Tass argued.
Raising anew the issue of basing new US missile in Western Europe -- a decision West Germany has reaffirmed, in delicate tandem with its call for arms talks -- Tass warned that the US neutron bomb decision would "further complicate and delay" such negotiations.
The Soviet government newspaper Izvestia later repeated this theme in tougher language.
The initial assumption among most foreign analysts was that the suggestion of possible difficulties on the negotiating front was part of Soviet media pressure on the West Europeans, rather than a signal that Moscow was rolling back on its months-old public bid for arms talks.
The Tass commentary added a further, if still nonspecific, warning of possible Soviet retaliation for the US decision on the new weapon:
"It can hardly be believed in London or Bonn," Tass said, "that while the West is being equipped with neutron weapons, measures in reply will not be taken by countries against which these weapons are intended to be used."
The Soviets argued that the generally low-key response fron NATO countries to the Reagan decision amounted to "connivance and encouragement" of the move.
"The governments of West European states . . . are capable of curbing, and bringing to its senses, their transoceanic [American] partner," Tass said.
That, of course, remains to be seen, especially since the Reagan administration has been careful to deny any plans to deploy the neutron weapon in West Europe at present.
But Western diplomats here point out that the only logical arena for the weapon -- a shell-mounted warhead portrayed as particularly effective against massive tank assaults -- would be Western Europe.
(Tass took up that point with the barbed question: "Is the Pentagon going to use this barbarous weapon in Nevada or Atlanta?")
"Whatever the neutron weapon's military qualities," remarked one foreign analyst, "its potency as a political weapon remains large. . . . It would be unrealistic to think the Soviet Union won't make it an important addition to its propaganda arsenal."
A Soviet official said that the USSR, whatever political benefits it might extract from the US go-ahead for the warhead, regretted Mr. Reagan's move.
But he added that the US administration seemed to have "no idea of [foreign] policy . . . of what is digestible" in the outside world.