India, Dec. 11 -- In what Indian officials and military analysts say is the clearest indication yet that Pakistan's F-16 fleet was affected during Operation Sindoor, the United States has approved a $686 million sustainment and systems-upgrade package for the fighter jets, a scale and composition that align closely with the damage documented at key Pakistan Air Force bases earlier this year.

The package, notified to the US Congress by the Defense Security Cooperation Agency (DSCA), covers an extensive suite of avionics, communications and mission-support upgrades that directly correspond to the categories of equipment and infrastructure that internal Pakistani documents, first reported by this newspaper, showed had been degraded in the a...