1. China operates in significant volume in Panama (like CK Hutchison Holdings, ports at Balboa/Cristobal etc) while Trump tried to pause China- Panama operations he only managed to slow them down a bit.
2. China continues to receive Venezuelan oil, but I agree that is more depended now on Iranian crude. Thats why it makes no 4 more crucial.
3. Not a standard practice, more-like a specific incident
1/2