- Summary- This content was produced in Russia where the law restricts coverage of Russian military operations in UkraineMOSCOW, Dec 28 (Reuters) - The rouble weakened sharply on Wednesday, sliding to the 72 mark against the dollar, as sanctions on Russian oil and their probable impact on export revenues put pressure on the Russian currency."The newly imposed Western sanctions have contributed to the recent falls in energy prices, which is certainly putting pressure on the rouble," said Olga Yangol, head of emerging markets research and strategy for Americas at Credit Agricole CIB.The rouble will be relatively resilient going forward though, Yangol added, expecting the oil price to be mainly driven by geopolitics and for OPEC+ to continue to trim its production in response to market fundamentals.Brent crude oil , a global benchmark for Russia's main export, was down 0.4% at $84.0 a barrel.President Vladimir Putin on Tuesday delivered Russia's long-awaited response to the Western price cap, signing a decree that bans the supply of crude oil and oil products from Feb. 1 for five months to nations that abide by the cap."