The United States and the Soviet Union made a further post-Cold War gesture Thursday to display their partnership at the United Nations although some differences emerged in their approach to the Persian Gulf crisis.

John Bolton, U.S. assistant secretary of state for international organizations, and Soviet Deputy Foreign Minister Valdimir Petrosky held their second joint press conference in a year to declare the end of "confrontational" relations and a willingness to make the United Nations "a real center for agreed common actions."Questioned immediately about their attitudes toward the use of force in the gulf, both men said the political and diplomatic options had not yet been fully explored.

Bolton said the United States was investigating the implications of Article 42 of the U.N. Charter, which says the Security Council may "take such action by air, sea, or land forces as may be deemed necessary to maintain or restore international peace and security."

But he said, depending on the situation, that "there was no doubt" that Washington had authority under Article 51 to act in defense of a nation under attack but said it was difficult to determine whether further U.N. approval was necessary.

Article 51 allows military action in self-defense "until the Security Council has taken measures necessary to maintain international peace and security."

Petrovsky, however, emphasized several times that any action had to be taken within the framework of the U.N. Charter, including the creation of a U.N. force.

The United States to date has avoided putting any of its 170,000 forces in the gulf under U.N. control, although it has agreed to the revival of a long-dormant U.N. military staff committee but limited its duties to an informational exchange.