AMMAN, Jordan, April 26--King Hussein placed Jordan under a military governor today and launched a determined war against the Communists in his kingdom.

As military governor for the whole country, the King named his new defense minister, Suleiman Toukan.

At the same time, the Arab Legion, the King's loyal and predominantly Bedouin army, began a roundup of Communists, left-wing leaders and extreme nationalists, in an attempt to snuff out the Red influence which has helped keep this nation in seething ferment.

U.S. Okays Suez Plan

UNITED NATIONS, N.Y., April 26--The United States today accepted Egypt's new Suez Canal plan on a trial basis but six other members of the U.N. Security Council said an international agreement is needed.

The six are Australia, Britain, Colombia, Cuba, France and Sweden. Iraq and the Soviet Union said it was all right as it stood.

U.S. Aids Jordan Rule

WASHINGTON, April 26--The United States disclosed today it has urgently cautioned Syria, Egypt, Israel and other governments against any drastic action which might further inflame the Jordan crisis.

The State Department reported this newest move to bolster young King Hussein's hand amid unconfirmed rumors that Russian volunteers might back up forces seeking to topple him.

Professors Criticize Firings

NEW YORK, April 26--The American Assn. of University Professors today accused the University of Nevada and Catawba College, Salisbury, N.C., of unfairly firing faculty members.

Delegates to the association's 43rd annual convention voted to censure administrations of the two institutions on the ground they violated principles of academic freedom and tenure.