Prime Minister Vladimir Putin of Russia visited Venezuela on Friday to sign a series of military and oil agreements with President Hugo Chavez, who is seeking to expand ties with Russia as a way of countering the influence of the United States in Latin America. Putin's one-day visit built on a relationship rooted in billions of dollars of Russian arms sales to Venezuela over the past decade. Venezuela has also emerged as one of Russia's most vocal supporters, recognizing two Russian-backed separatist enclaves of Georgia in 2009 and applauding Russian efforts to advance the ambitions of an embryonic group of gas-rich nations. Russia's warm ties with Venezuela are also opening the way for it to improve relations with a handful of other countries in Latin America, notably Bolivia. President Evo Morales of Bolivia, a staunch critic of the Obama administration and a major recipient of Venezuelan aid, was also expected to discuss cooperation agreements with Putin here on Friday night. Still, obstacles persist to a more assertive Russian expansion in Venezuela beyond the sphere of weapons sales and political engagement with Chavez's allies. As if to illustrate these challenges, the highlights of Putin's visit included the sale of 2,250 Russian-built Lada vehicles to Venezuela's government, and the delivery of four MI-17 helicopters to Chavez's military, even though Chavez had suggested before Putin's arrival that the countries could cooperate ambitiously on nuclear energy and a satellite-launching base in Venezuela. Relatively low oil revenues in both Russia and Venezuela may also hamper their plans to build complex and expensive oil projects in southern Venezuela. One oil venture discussed by senior Venezuelan and Russian officials here this week would require at least $18 billion in investments. Still, Putin signaled seriousness over Russia's oil ambitions here by agreeing to pay $600 million in signing fees. Skepticism also lingers over Russia's capacity to expand its influence in the hemisphere after the Soviet Union, with more resources, achieved few tangible results in Central and South America during the Cold War. 'Russia, whatever its leaders' ambitions, mostly lacks the wherewithal to mount an enduring diplomatic and economic offensive in Latin America,' said Stephen Kotkin, a Russia specialist at Princeton University. Disarray in Venezuela's oil industry has contributed to intensifying electricity blackouts, not to mention undermining its ability to play a more influential role in the gas-exporters group that Russia is supporting. Venezuela still needs to import natural gas from neighboring Colombia and has been unable to increase its own natural gas output to fuel power plants around the country. Chavez insisted in a news conference on Friday that Venezuela and Russia were prepared to work together to build nuclear energy projects here to alleviate the electricity shortages (officials here have also referred to nuclear cooperation with Iran). But the timing of such projects remains vague, and the cost and scientific expertise needed to carry out such plans remain outside of Venezuela's reach, according to studies by independent nuclear specialists. 