What can those spies in the sky see?

Ever since Pearl Harbor, the chief obession of American intelligence officers has been to provide warning against surprise attack.

While they have had trouble in the past predicting political events, in the military realm US intelligence officers are certain that they could warn of any major Soviet attack against the NATO forces in Europe. This is in part thanks to extraordinary developments in photographic intelligence, some of it provided by spy-in-the-sky satellites, but some of it of an even more rapid nature.

In its current edition, the Armed Forces Journal reports on new ''electronic cameras,'' whose sharp images of a European battlefield can be relayed instantaneously from an airplane or from space stations to locations as far away as the White House. High-resolution images can be obtained through haze, smog, or light mist. The new cameras, says the magazine, ''must now cause Soviet war planners to think twice about even their cleverest surprise attack options.''

''No longer does a commander have to wait hours for a hard-copy printout of imagery taken from an airplane, from a small, remotely piloted vehicle, or from a satellite to confirm to his higher-ups that a surprise attack is imminent,'' says the Journal.

The Journal says that the existence and capabilities of the electro-optical sensors that it describes have hitherto been highly classified. Former President Carter alludes to their use, however, in his just released memoirs, ''Keeping Faith.'' In the book, Mr. Carter says that satellite photographs of the US Embassy compound in Tehran and of the surrounding area - taken before the abortive 1980 mission was launched to rescue the American hostages held there - kept the White House abreast of any changes in the Iranian captors' habits and in the composition of their units.