The United States and China hold views that converge on key regional issues and Washington does not fear an improvement in Sino-Soviet relations, U.S. Undersecretary of State Michael Armacost said today.

The high-ranking State Department official also said that the Reagan administration hoped soon to be able to submit to Congress the long-stalled U.S.-China agreement on nuclear cooperation, but he added that details of its implementation were still being discussed with the Chinese.

Asked at a press conference at the U.S. Embassy here about the apparent failure of the Chinese to follow up on threats made over the past few months to teach Vietnam a "second lesson," Armacost said that based on recent press reports, there has been "a considerable bit of activity" on the China-Vietnam border. At the same time, he said, "I didn't have the impression that an invasion was in prospect."

Armacost confirmed that plans had been made for U.S. Navy ships to make a port call in China for the first time in more than three decades. But he said he did not expect a port visit to take place for another six to eight weeks at a minimum.

Armacost was speaking at the end of a three-day visit to Peking during which he discussed with Chinese Foreign Minister Wu Xueqian and Vice Minister Zhu Qizhen what he described as "broad regional and global issues."

He said there was a "considerable focus on East-West issues and our respective ties with the Soviet Union in light of recent developments there."

Some recent reports from Washington have suggested that administration officials are concerned that the Chinese have made a series of friendly gestures toward the new Soviet leader, Mikhail Gorbachev, without obtaining any apparent concessions from the Soviets on key issues.

In the past, the Chinese have indicated that relations with the Soviet Union could not be normalized until the Soviets dealt with the "three obstacles" -- the Soviet troop presence along the Chinese border and in Mongolia, the Soviet invasion of Afghanistan, and Soviet support for Vietnam's actions in Cambodia.

"I think there is a convergence of views on those issues" between the United States and China, Armacost said, in reply to a question.

Asked about recent moves by the Chinese and Soviets that seem to be aimed at improving their relations, Armacost noted that there had been some increases in Soviet trade and exchanges with China "but there have likewise been increases in our exchanges with the Soviet Union and in light of the change in Soviet leadership, I think it's quite natural for countries to assess whether or not it's possible to secure some improvement in those relations."

Asked whether the United States would welcome an improvement in Sino-Soviet relations, Armacost said, "We certainly don't fear an improvement in Sino-Soviet relations . . . . We're exploring the possibility of improving our own relations with the Soviet Union."

Asked to characterize the talks he held with the Chinese, Armacost described them as "friendly and cordial and and extremely productive."