this 2002 article has many details:
[commondreams.org]

Nixon's hitman ... Despite being responsible for war crimes he got the Nobel Peace Prize. The most visible éminence grise of American post WW2 politics.

If you are curious why didn't you Google him?

Christopher Hitchens wrote about how Kissinger was a war criminal:

[en.wikipedia.org]

Yes. He fucked our currency. Built it on a house of cards that will fall when the petrodollar finally becomes obsolete. It's a big part of the reason for most of our military actions over the past 45+ years, regardless of what spin politicians and the media try to put on things.

War criminal. Worse than Dick Cheney.

Now there's a complicated individual. There is an awful lot there to unpack.
Brilliant mind, master negotiator and diplomat. Complete asshole and war criminal.
Nixon's enabler.

There is more to know about him than you could pick up through Wikipedia.
Your local library probably has quite a number of biographies to choose from.
Definitely read more than one, just to get more perspectives.

I remember him well. He came off as being a freakin' diplomatic genius back in the 70s. The further out one gets from that time, the more there is learn about him.

War criminal. Illegal bombing in non aggressive countries. Destabilized the region causing millions of deaths