Washington, Jan. 24: The guns will fall silent and a ceasefire will go into effect throughout Vietnam on Sunday morning (8 a.m. Saigon time). Disclosing this in a short television address to his war-weary nation last night, President Nixon confirmed that his principal negotiator, Dr. Kissinger, and North Vietnam’s Mr. Le Duc Tho had initialled an agreement to that effect in Paris earlier in the day. After declaring that the agreement would bring the peace with honour he had always insisted on, Mr. Nixon said that the remaining 24,000 American troops in South Vietnam would be withdrawn during the 60 days following the ceasefire. During the same period, the North Vietnamese have agreed to return the 597 American prisoners of war captured in various parts of Indo-China, and account for the 1,335 Americans listed as missing in action. Mr. Nixon left it to Dr. Kissinger to announce the details of the agreement and said that the pact would be formally signed at a ceremony in Paris on Saturday. Speaking with restraint and hardly any trace of self-congratulation, Mr. Nixon also disclosed that the ceasefire, which would be supervised by an international force drawn from Canada, Hungary, Indonesia and Poland, had the support of President Thieu of South Vietnam.