Star Trek VI: The Undiscovered Country1991

Spock:
Good morning. Two months ago, a Federation starship monitored an explosion on the Klingon moon, Praxis. We believed it was caused by overmining and insufficient safety precautions. The moon's decimation means a deadly pollution of their ozone. They will have depleted their supply of oxygen in approximately 50 Earth-years. Due to their enormous military budget, the Klingon economy does not have the resources with which to combat this catastrophe. Last month, at the behest of the Vulcan ambassador, I opened a dialogue with Gorkon, Chancellor of the Klingon High Council. He proposes to commence negotiations at once.

Admiral Cartwright:
Negotiations for what?

Spock:
The dismantling of our space stations and starbases along the Neutral Zone, an end to almost 70 years of unremitting hostility which the Klingons can no longer afford.