• US intelligence indicates China is preparing to deliver air defense systems to Iran.
• Shipments may be routed through third countries.
• Systems include shoulder-fired anti-air missile systems known as MANPADs.
• US and Iran set to hold high-level negotiations in Pakistan.

This development may signal a significant escalation in the conflict between the US and Iran, with China's involvement potentially altering the regional balance of power. The use of third countries for shipment routing suggests an attempt to evade detection, which could indicate a broader strategy of covert support.