Criticising Pak in 1971 would have destroyed US-China talks:

The Pakistani channel of talks between America and China would have collapsed if the US had publicly condemned human rights violations and atrocities by Pakistan army against the people of then East Pakistan, former US Secretary of State Henry Kissinger has said.
In an interview to The Atlantic magazine, which has been published in its latest issue, Kissinger said by the time when the Bangladeshi crisis began in March 1971, the US had conducted a number of highly secret exchanges with China and were on the verge of a breakthrough.
"These exchanges were conducted through Pakistan, which emerged as the interlocutor most acceptable to Beijing and Washington. The Bangladesh crisis, in its essence, was an attempt of the Bengali part of Pakistan to achieve independence. Pakistan resisted with extreme violence and gross human-rights violations," Kissinger said.

"To condemn these violations publicly would have destroyed the Pakistani channel, which would be needed for months to complete the opening to China, which indeed was launched from Pakistan," he said.
The then Nixon administration considered the opening to China as essential to a potential diplomatic recasting towards the Soviet Union and the pursuit of peace.
"The US diplomats witnessing the Bangladesh tragedy were ignorant of the opening to China. Their descriptions were heartfelt and valid, but we could not respond publicly. But we made available vast quantities of food and undertook diplomatic efforts to resolve the situation," he said.

"After the opening to China via Pakistan, America engaged in increasingly urging Pakistan to grant autonomy to Bangladesh. In November, the Pakistani president agreed with Nixon to grant independence the following March," Kissinger said.

"The following December, India, after having made a treaty including military provisions with the Soviet Union, and in order to relieve the strain of refugees, invaded East Pakistan (which is today Bangladesh)," he said, adding that the US had to navigate between Soviet pressures; Indian objectives; Chinese suspicions; and Pakistani nationalism.
Kissinger said adjustments had to be made-and would require a book to cover-but the results require no apology.

"By March 1972-within less than a year of the commencement of the crisis-Bangladesh was independent; the India-Pakistan War ended; and the opening to China completed at a summit in Beijing in February 1972. A summit in Moscow in May 1972 resulted in a major nuclear arms control agreement (SALT I)," he said.
"Relations with India were restored by 1974 with the creation of a US-Indian Joint Commission (the Indo-US Joint Commission on Economic, Commercial, Scientific, Technological, Educational and Cultural Cooperation], which remains part of the basis of contemporary US-India relations. Compared with Syria, Libya, Egypt, Iraq, and Afghanistan, the sacrifices made in 1971 have had a far more clear-cut end," he argued.