I guess it's not so joint anymore.
NYTIMES: The British energy giant BP moved closer to losing control of its joint venture in Russia after the operation’s chief executive was forced to leave the country Thursday because he could not get a work visa. The development is the latest twist in a rising nationalism that is shutting Western oil companies out of energy-rich regions and has wide implications for BP, which pumps about a quarter of its worldwide oil output in Russia.
While BP retains ownership of 50 percent of the TNK-BP venture, the departure of the executive, Robert Dudley, an American, will probably lead to the passing of greater operational control to the Russian partners. Mr. Dudley called his departure “temporary,” but it was unclear when he might return, or how he would manage the company, which has more than 60,000 employees and nearly 100 subsidiaries, from outside the country. About 50 expatriate staff members remain at TNK-BP, though not all have received work visas.
The article does not mention why Dudley's visa was denied. Speculations?