With Americans filling the roles of CEO, chief financial officer and executive director, Yukos may in part be seeking to protect itself from the pressures of the Prosecutor General's office and the Russian government.

Khodorkovsky, whose arrest on fraud and tax evasion charges sparked a drop in Yukos shares and, in turn, a plunge in the Moscow Stock Martet, resigned as CEO on Monday, saying he wants to deflect the blows from his company.

His replacement will be Simon Kukes, who was born in Russia but emigrated to the US 30 years ago. Kukes will be joined by Steven Theede, also an American, as executive director of Yukos-Moscow, a subsidiary under which many of Yukos' central corporate functions are incorporated.

The pair will join another US citizen, Bruce Misamore, who remains Yukos' chief financial officer.

Kukes, the standing chairman of the Yukos board of directors, was formerly president and chief executive officer of the Tyumen Oil Company, or TNK, which merged with BP's Russian subsidiary earlier this year. He also was a director of global drilling outfit, Parker Drilling.

Although suitably qualified to fill the position analysts believe Kukes' shift to CEO is motivated by the fact prosecutors will be more hesitant to arrest American citizens. The US State Department has already expressed concerns about the freezing of Yukos shares and other moves against the company since Khodorkovsky's arrest.

The US has also expressed fears that the detention may affect investor confidence in Russia's booming economy.

Yukos shares climbed 3.9% in Moscow trading Monday immediately after Khodorkovsky announced his resignation as chief executive. Shares ended up 12% at $12.65 -- though they remain more than 20% below their all-time high, which was posted shortly before Khodorkovsky's arrest.