VIENNA, NOV. 18 -- NATO and Warsaw Pact arms negotiators initialed the Treaty on Conventional Armed Forces in Europe today, hailing the accord as a historic contribution to international security.

"With this treaty the Soviet Union is ceasing to be a military state," declared Soviet chief negotiator Oleg Grinevsky. It "will fundamentally change our everyday life. . . . All the wealth of our society can now be used for the benefit of the people instead of building up an expensive and, let's be frank, sometimes useless war machine."

The initialing occurred behind the closed doors of the Hofburg palace here to avoid stealing the limelight from Monday's summit meeting in Paris, where the formal signing will take place. But the diplomats who have hammered it out over the past 20 months met with journalists afterward to highlight the significance of their work.

R. James Woolsey, the chief U.S. negotiator, told a news conference that the ceremony marked "the beginning of a very important new period in European history." The accord will "lock in" political gains achieved by movements such as Poland's Solidarity and the Czechoslovak Civic Forum. These gains "make it a matter of many, many months rather than a few days before any country can undertake a surprise attack" on another European state, according to Woolsey.