Soviet President Mikhail S. Gorbachev signed a historic non-aggression treaty with Chancellor Helmut Kohl Friday and got a hero's welcome for letting the Berlin Wall and Iron Curtain collapse.

Gorbachev's first visit to united Germany came on the first anniversary of the opening of the Berlin Wall, a fitting coincidence because his reforms helped bring the Cold War barrier down.Both Kohl and Gorbachev stressed the importance of the historical changes that have allowed closer ties as they signed the broad agreement that is to serve as the foundation of future relations.

"Having signed this document one could hardly . . . think about until recently, we have officially ended a whole historical process and opened a deep perspective for ourselves," said Gorbachev.

In the treaty, initialed in Moscow on Sept. 13, both nations pledge not to attack the other and to honor the borders of all European nations.

A short-lived alliance between Germany and the Soviet Union at the start of World War II contributed to the deaths of 27 million Soviet citizens when the allies became foes.

"We are closing the book on the painful past and clearing the way for a new beginning," Kohl said in a speech at the signing ceremony.

Gorbachev arrived at Cologne-Bonn airport Friday morning in an Ilyushin-62 and was met by a 27-man German military honor guard.

He was greeted by Foreign Minister Hans-Dietrich Genscher and gave a hearty wave as he stepped out of the plane.