China is a primary adversary for the US. Oil is a major resource for both countries, supporting economics and defense.

First, observe the top 10 oil reserve countries:

1. Venezuela: ~303–304 billion barrels (mostly heavy crude) 2. Saudi Arabia: ~267 billion barrels 3. Iran: ~208–209 billion barrels 4. Canada: ~163–170 billion barrels (mostly oil sands) 5. Iraq: ~145–147 billion barrels 6. United Arab Emirates (UAE): ~111–113 billion barrels 7. Kuwait: ~101 billion barrels 8. Russia: ~80–110 billion barrels (estimates vary) 9. United States: ~40–70 billion barrels (reserves fluctuate with prices/technology) 10. Libya: ~48 billion barrels

China is the world's largest oil importer. Stats are hard, things get mislabeled due to sanctions, but somewhere between 15%-20% of China's oil is-or-was from Iran+Venezuela.

In my view, this partially explains the move in Iran, considering a 3-10 year strategic timeline.