According to three US intelligence sources cited by CNN, China is preparing to ship shoulder-fired anti-air missiles known as MANPADS to Iran. These are weapons a single person can operate to shoot down low-flying aircraft, exactly the kind of threat US planes faced during the five-week war.

This didn’t come out of nowhere. Last week, Trump confirmed a US F-15 fighter jet was shot down over Iran by a “handheld shoulder missile, a heat-seeking missile.” Iran only said it used a “new air defense system.” No one confirmed if it was Chinese-made, but the pieces of the puzzle are starting to fit.

According to reports, Beijing is routing shipments through third countries to conceal their origin. Chinese companies had already sent rocket fuel precursor chemicals, and five Iranian-owned ships transported what appears to be sodium perchlorate, a key ingredient for solid-fuel ballistic missiles.