The nation's top-ranking military officer warned yesterday that "without question" the United States "must prepare for difficulties down there" in Panama if the Senate fails to approve the canal treaties.

Air Force Gen. George S. Brown, chairman of the Joint Chiefs of Staff, sounded this warning yesterday in addressing a group of about 40 newspaper publishers visiting the Pantagon.

Colonialism "has become a very, very strong emotional cause" with the Panamanians, Brown told the government affairs committee of the American Newspaper Publishers Association.

There will be "trouble" for certain if the Senate fails to go along with the treaties, he continued. "How serious I don't know," Brown said.

Declaring that some critics have argued there may well be trouble in Panama even if the treaties are approved, Brown said that is only "a possibility" while failure to approve makes trouble "a certainty."

The Joint Chiefs of Staff, Brown said, "are proud" that the formula they recommended for turning over the canal to Panama by the year 2000 without denying the United States its use was adopted by the negotiatiors.

"We've had a hand in this for years," Brown said of the chiefs' role in shaping the treaties. The strategic value of the canal to the United States "rests in its use, not its ownership," he said.

Brown said he had addressed a group of retired officers in an earlier session to explain the chiefs' support of the canal treaties. He said the meeting was in response to retirees' requests and did not constitute any attempt to sell them on the value of the treaties.