The Chinese Prime Minister, Mr. Chou En-lai, left Hanoi today [March 8] after an unannounced four-day visit officially described as a “severe warning to the American aggressors.” Mr. Chou said during a speech while here that “the Chinese people will not be afraid to make the greatest sacrifice to aid the Indo-Chinese people until final victory.” Mr. Chou arrived here last Friday at the head of a communist party and government delegation including the top-ranking military officials, the Chief of Staff and Deputy Chief of Staff of the Army. For security reasons, an embargo was placed on the news of his arrival. Speaking before several thousand residents of Hanoi, Mr. Chou declared: “the Vietnamese, Laotian and Cambodian peoples are brothers-in-arms united in life and death. We shall fight together, we shall win together. The United States will be defeated.” Mr. Chou said his country had made “adequate preparations” to meet the continued U.S. war efforts in Indo-China. The U.S. Government must be responsible for all the “serious consequences” arising from such military action, he warned. He did not specify the preparations China has made.