US penalties target China's tanker trade.
The government is pushing domestic production to counter import dependence concerns.
Higher costs could add to growth slowdown and trade war woes.
This would not be the first time that China has pressured ExxonMobil to steer clear of oil exploration and production in Vietnam.
Pollution may rise as cities are urged to ease restrictions on sales.
Chinese and Lao dam projects, melting glaciers pose grave threats down river.
The state-owned oil company reportedly backs pipeline route that Russia opposes.