During the turbulent and transformative early 1990s, Diego Arria was Venezuela’s ambassador to the United Nations and president of the United Nations Security Council.

Now, Arria — who has written about Balkan war crimes and helped negotiate peace in El Salvador and Haiti in the ’90s — has listed his Upper East Side duplex inside a Gilded Age mansion for $4 million.

Arria bought the co-op for $3 million in 2013, according to property records.

The tony, renovated residence is at 17 E. 63rd St. between Fifth and Madison avenues. It occupies the first two floors of a 30-foot, five-story limestone mansion that dates to 1901.

The home comes with two bedrooms, 2½ baths, and boasts 21-foot-high ceilings and window walls overlooking a terraced garden.

There’s a living room with high ceilings and a working fireplace, an open dining area and encased French doors that lead to a private walled garden.

On the lower level, there’s a two-story-high set of windows, a home office nook, a wine alcove, a kitchen and lots of storage.

The listing brokers for Arria’s first-floor duplex are husband-and-wife duo James and Anna Hall of Compass. 

A second, 2,136-square-foot, second-floor co-op has also hit the market for $4.25 million. That’s listed by Corcoran’s Paul Kolbusz.