Paris — Helped by his new offer on arms control, President Reagan looks set to attend the Geneva summit with strong support from his European allies. Europe had been pressuring the United States for a new arms control initiative. It was needed, the Europeans said, to counter the bad impression given by fighting within the Reagan administration over how to respond to a Soviet proposal to cut strategic missiles by 50 percent.
For this reason, even before some details of Mr. Reagan's proposal leaked out, a series of effusive editorials appeared across the continent.
``Something is decidedly changing in East-West relations over arms control,'' exclaimed the Paris daily Le Monde in a front-page opinion piece, which struck a responsive chord throughout the continent. ``The climate . . . is clearing.''
European arms analysts add notes of caution, however. ``What are the Americans actually proposing?'' asks Jonathan Alford of the International Institute of Strategic Studies in London.
``As a sign of flexibility [the announced proposal] is sure to please the Europeans. But until we know exactly what it means,'' he says, ``we're scratching our heads.''
Mr. Alford and other analysts here emphasize two points they would like cleared up:
President Reagan's program of research into space-based defense. At a NATO meeting this week, Britain dropped its objections to participating in the program, called the Strategic Defense Initiative. This may lend support to West Germans who favor their country's participation in the program.
Still, Europeans insist that Reagan must negotiate with the Soviets about his strategic defense plans. The biggest question for Europe is: Will the President compromise or will he remain set on pursuing the program he says threatens no one?
The French and British nuclear forces. Soviet leader Mikhail Gorbachev insists that these must figure in negotiations over East-West nuclear forces. Britain and France object to this and want to make sure Reagan will stick to his longstanding opposition to including European forces in strategic negotiations.
``Will the American definition of `strategic' weapons include our missiles?'' asks Jonathan Alford in London. ``It's unclear how that will play out in Geneva.''
The recent Soviet proposal for arms cuts put the key European allies in a difficult position. While both Britain and France felt obligated to refuse the Soviet offer to negotiate their own nuclear arsenals separately, they worried that the West was appearing intractable. West Germany shared this concern. So did the Dutch government, which was in the process of finalizing its decision to allow deployment of NATO nuclear missiles on its territory. That decision was approved Friday.
European worries increased when news of fighting within the Reagan administration over arms control strategy reached the public.
European leaders voiced their concern, first directly to Reagan at the recent Western mini-summit in New York, then to US officials at last week's NATO meeting in Brussels. The Europeans reportedly pushed for a new US initiative.
When news of the initiative came, few Europeans believed Reagan was acting only to please them. Officials say the President is well aware of the necessity to take the public relations offensive.
As Gerard Dupuy of the French daily Lib'eration wrote, ``the reason for the Reagan softening was Gorbachev's media sucess.''
To keep the Western alliance strong, Europeans say the hopeful signs they see in the new Reagan initiative must be confirmed at the summit Nov. 19 and 20 in Geneva. At least now, they say, the signs are promising.
``Reagan will go to Geneva strengthened by a solidarity almost without fault of his allies -- the Dutch decision crowning everything,'' says Mr. Dupuy. ``The curtain at Geneva may not yet be up, but the setting is in place.''