The aircraft can also be operated as a military command center in the event of an incident such as a nuclear attack. Operational modifications include aerial refueling capability and anti-aircraft missile countermeasures. The electronics on board are connected with approximately 238 miles (383 km) of wiring, twice that of a regular 747. All wiring is covered with heavy shielding for protection from a nuclear electromagnetic pulse in the event of a nuclear attack. The aircraft also has electronic countermeasures (ECMs) to jam enemy radar, flares to avoid heat-seeking missiles, and chaff to avoid radar-guided missiles. All small arms and ammunition stores not in the physical possession of the Secret Service on board the VC-25s are stowed and secured by the Secret Service in separate locked compartments, each with a different locking mechanism for added security. Many of the VC-25's other capabilities are classified for security reasons.