Saudi Arabia has been trying to pressure President Vladimir V. Putin of Russia to abandon his support for President Bashar al-Assad of Syria , using its dominance of the global oil markets at a time when the Russian government is reeling from the effects of plummeting oil prices. Saudi Arabia and Russia have had numerous discussions over the past several months that have yet to produce a significant breakthrough, according to American and Saudi officials. It is unclear how explicitly Saudi officials have linked oil to the issue of Syria during the talks, but Saudi officials say — and they have told the United States — that they think they have some leverage over Mr. Putin because of their ability to reduce the supply of oil and possibly drive up prices. “If oil can serve to bring peace in Syria, I don’t see how Saudi Arabia would […]