Standing firm on U.S. policy, President Bush has placed the onus on West Germany to remove a threat to unity at a May 29-30 NATO summit by moder-ating its call for negotiations on short-range nuclear missiles.

Speaking to reporters Thursday after talks with Canadian Prime Minister Brian Mulroney, Bush said he remains "always willing to negotiate" a NATO position that recognizesWest Germany's sensitivity about the missiles on its soil.

But in hinting the door may be open to eventual negotiations on short-range nuclear forces, he held to U.S. demands that such talks only follow cuts in conventional forces and not lead to elimination of nuclear arms from Europe.

"We're not going to go for any `third zero' or getting SNF out of whack in terms of negotiations," he said. "So let's be clear on that."

His comments would not preclude support in principle for future negotiations on certain terms but would require West Germany to qualify its support for talks on short-range forces to resolve the dispute for the summit.

"I want the summit to be a success," Bush said.

The potential crisis within NATO was created when West German Chancellor Helmut Kohl moved to protect his left political flank by urging early East-West negotiations on short-range nuclear forces.

His surprise move, which won general support from Norway, Denmark, Greece, Belgium, Italy and Spain, came after U.S. officials thought another threat to unity had been averted by deferring firm decisions on the modernization of NATO missiles in West Germany.

Mulroney said NATO must adopt a position rooted in principles of "total solidarity" and a "common view" of American leadership.

"This is not an association of free-lancers," he said. "We have a common NATO position. And while there are divergences of views that emerge from time to time, the object of our getting together is to harmonize those views in one position.."

Indeed, positions staked out in recent days on each side of the Atlantic have offered outlines of compromise: modernization of NATO nuclear arms would move forward as long as the Soviets maintain superiority in conventional forces.