They did.
In 1971, Nixon ensured that West Pakistan remained intact.
They repeatedly asked China for military help - but China never provided any.
Nixon: Does State understand that?
Kissinger: No. Well they understand it now, believe me.
Nixon: Yeah. See the point is, our desire is to save West Pakistan. That’s all.
Kissinger: That’s right. That is exactly right.
Nixon: All right. Fine. What is State up to now? We’re still getting, you’re still getting those—keep those carriers moving now.
Kissinger: The carriers—everything is moving. Four Jordanian planes have already moved to Pakistan, 22 more are coming. We’re talking to the Saudis, the Turks we’ve now found are willing to give five. So we’re going to keep that moving until there’s a settlement.
[Omitted here is conversation unrelated to South Asia.]
Nixon: When are you going to see the Chinese? This afternoon?
Full conversation -
https://2001-2009.state.gov/r/pa/ho/frus/nixon/e7/48542.htm
Nixon hated India and Indians with a passion even the Pakistanis couldn't match.