(Reuters) -Lockheed Martin ( LMT ) reported on Tuesday that its second-quarter profit plunged by about 80%, after the U.S. defense giant recorded pre-tax losses of $1.6 billion, mainly linked to a classified program within its Aeronautics segment.

The company's shares fell 8% in premarket trading.

Its net income dropped to $342 million, or $1.46 per share, compared with $1.64 billion, or $6.85 per share, a year earlier

Lockheed said the charge stemmed from difficulties with a classified program in its Aeronautics business and to certain international helicopter programs in its Sikorsky unit.