Biden was sworn in on January 5, 1973, by the secretary of the Senate Francis R. Valeo at the Delaware Division of the Wilmington Medical Center. Present were his sons Beau (whose leg was still in traction from the automobile accident) and Hunter and other family members. At 30, he was the sixth-youngest senator in U.S. history.
Shah of Iran announces that the 1954 operating agreement between a consortium of oil companies and Iran will not be renewed when it expires in 1979. The consortium was formed in 1954 as a means to settle a dispute between a new ministry in Iran and the Anglo-Iranian Oil Company (AIOC). The consortium included Standard Oil of New Jersey, Standard Oil of California, SOCONY-Vacuum, the Texas Company, Gulf, Royal Dutch-Shell, the Compagnie Francaise de Petroles, and the AIOC.
On 15 January 1973, all U.S. combat activities were suspended. Lê Đức Thọ and Henry Kissinger, along with the Provisional Revolutionary Government (PRG, the Viet Cong's government) Foreign Minister Nguyễn Thị Bình and a reluctant President Thiệu, signed the Paris Peace Accords on 27 January 1973.
In the lead-up to the ceasefire on 28 January, both sides attempted to maximize the land and population under their control in a campaign known as the War of the flags, fighting continued after the ceasefire, this time without US participation and continued throughout the year.