Regional instability is the greatest threat facing Asia-Pacific nations, Adm. Charles Larson, commander in chief of the U.S. Pacific Command, said Monday in a speech focusing on the Soviet Union.

In a keynote address to a conference in Australia on naval power in the Pacific, Larson said instability and Soviet expansion were disturbing trends in the region and the outlook was not reassuring.He cited new demands by ethnic groups, nationalists and religious extremists, uneven economic progress creating friction between nations, accelerating population growth and environmental problems.

"Given the growing importance of regional stability and the growing list of regional issues, I do not find the long-term trends reassuring," Larson said.

He said Soviet political reform had slowed recently and in some ways been reversed, but Soviet military capability in the Pacific continued to grow.

"A second disturbing trend is the Soviet effort to expand their influence in Asia and the Pacific," Larson added.

"Whether their initiatives work to everyone's benefit, or ultimately promote instability as in the `bad old days' of communist expansionism, remains to be seen," he said.

"So to summarize, the world I see for the future will be less stable but more dependent on regional stability than ever before," he told the conference of academic and government naval specialists from Australia, North America and Britain.