(CNN) The US is looking into reports that Pakistan misused American-made F-16 jets during an aerial engagement with India last week that brought the two nuclear armed neighbors to the brink of conflict.

Both India and Pakistan launched airstrikes over the Line of Control -- the de facto border that separates the two countries in disputed Kashmir -- in the first such incursion since 1971. An Indian jet was shot down in the dogfight and its pilot held in Pakistan custody for several days before Islamabad released him back to New Delhi on Friday.

The Indian Air Force said that Pakistan used US-made F-16 fighter jets in the raid that brought down the Indian pilot on Wednesday, in a possible violation of the terms of use by the US.

Pakistan has stated that no F-16s were used in the operation, though it hasn't specified what military equipment was involved.

A US Department of State official told CNN that it was "aware of reports" that the use of F-16 jets may have been in violation of the terms of use agreement and is "looking into them."