Answer by taking a quote from the following article:

Henry Alfred Kissinger (; German: ['kIsINGa]; born Heinz Alfred Kissinger, May 27, 1923) is an American political scientist, diplomat and geopolitical consultant who served as the United States Secretary of State and National Security Advisor under the presidential administrations of Richard Nixon and Gerald Ford. A Jewish refugee who fled Nazi Germany with his family in 1938, he became National Security Advisor in 1969 and United States Secretary of State in 1973.

Under Kissinger's guidance, the United States government supported Pakistan in the Bangladesh Liberation War in 1971. Kissinger was particularly concerned about the expansion of Soviet influence in the Indian Subcontinent as a result of a treaty of friendship recently signed by India and the USSR, and sought to demonstrate to the People's Republic of China (Pakistan's ally and an enemy of both India and the USSR) the value of a tacit alliance with the United States.  Kissinger sneered at people who "bleed" for "the dying Bengalis" and ignored the first telegram from the United States consul general in East Pakistan, Archer K. Blood, and 20 members of his staff, which informed the US that their allies West Pakistan were undertaking, in Blood's words, "a selective genocide". In the second, more famous, Blood Telegram the word genocide was again used to describe the events, and further that with its continuing support for West Pakistan the US government had "evidenced [...] moral bankruptcy". As a direct response to the dissent against US policy Kissinger and Nixon ended Archer Blood's tenure as United States consul general in East Pakistan and put him to work in the State Department's Personnel Office.  Henry Kissinger had also come under fire for private comments he made to Nixon during the Bangladesh-Pakistan War in which he described Indian Prime Minister Indira Gandhi as a "bitch" and a "witch". He also said "The Indians are bastards", shortly before the war. Kissinger has since expressed his regret over the comments.

What happened to him during the Bangladesh war?
Under Kissinger's guidance, the United States government supported Pakistan in the Bangladesh Liberation War in 1971.