Was Flipper a double agent for the KGB? The History Channel series “Inside the Soviet Military Machine” concludes with “Dolphin Soldiers” (8 p.m.). As strange as it sounds, these smart swimmers became pawns in the Cold War. As the arms race heated up, neither Washington nor Moscow wanted to fall into a Dolphin gap, so marine mammals were drafted into service on both sides of the Iron Curtain.

The Soviets created an elite cadre of slippery soldiers based in the Black Sea. They were trained to defend naval bases, locate underwater mines, intercept and attack enemy frogmen and even parachute from airplanes. The Soviets also performed cruel and grisly experiments on their flipper forces to learn the secrets of their speed, adaptability and their super hearing.

The collapse of the Soviet Unions left the dolphin-soldier program high and dry. Sadly, many of these former defenders of the Motherland were consigned to the indignity of zoos and marine theme parks. Others were re-trained to work with disturbed children. Like other Soviet military secrets and hardware, some of these swimming commandos could have fallen into the wrong hands. Rumors abound that rogue states, including Iran and Iraq, have purchased these dangerous dolphins.

Maestro Kurt Masur celebrates his 75th birthday and conducts his very last concert as music director of the New York Philharmonic on “Live From Lincoln Center” (7 p.m., PBS, check local listings). Musical highlights include: The Overture to “Candide” by Leonard Bernstein; “Incidental Music to A Midsummer Night’s Dream: Nocturne & Scherzo” by Felix Mendelssohn; Act III Introduction from “Madame Butterfly” by Giacomo Puccini; “Scheherazade: Festival at Baghdad” by Nicolai Rimsky-Korsakov and “Bolero” by Maurice Ravel. Beverly Sills hosts.

Tonight’s other highlights

Jonathan Frakes is host of “Beyond Belief: Fact or Fiction” (7 p.m., Fox).

Billy Zane stars as a comic strip super hero in the 1996 adventure “The Phantom” (7 p.m., ABC).

Shepard Smith is host of news magazine “The Pulse” (8 p.m., Fox).

Daljit Dhaliwal, former BBC journalist, and James Rubin, former U.S. assistant secretary of state, are hosts of “Wide Angle” (8 p.m., PBS, check local listings) a news magazine devoted to a single foreign affairs story.

Jack Nicholson and Jessica Lange take a roll in the dough in the torrid 1981 remake of James Cain’s potboiler “The Postman Always Rings Twice” (8 p.m., TNN).