KARACHI, Pakistan, Aug. 10 —Pakistan has reacted with surprise and concern to the signing of the pact between India and the Soviet Union, which Pakistan apparently regards as a defense treaty.

Although there was no official comment here, Government sources privately questioned why India, which they described as a major military power, still needed the agreement.

India's attitude, they asserted, was likely to become bellicose instead of just obnoxious. The circles said the treaty “knocks the bottom out” of India's contention that she is nonaligned.