Objective The paper aims to synthesis the impacts of Crimea's annexation into Russia on EU's energy diversification strategy, as well as the natural gas pipelines competitions in the Black Sea basin.

Methodology/Technique Based on secondary documentary research method, more than 10 in press articles and journals in the related studies field are found, then synchronizing their findings into comprehensive paragraphs.

Findings Firstly, the annexation of Crimea is an additional value to Russia's from the perspectives of economics, and military strength. Secondly, South stream pipeline would remain as one of the biggest competitors for EU after this annexation process; also EU would need to rectify its threat and so to diversify their natural gas market in order to avoid over-dependent on Russian's gas. Finally, Russia in this case would become a dominant gas player after this Crimea's annexation.

Novelty : Although there are many studies addressing this topic, most of them just address part of the issue. This paper, based on the latest extensive findings from previous research in press articles, reviews, journals, and case studies, give readers a holistic view of the Crimea's annexation into Russia.

Type of Paper: Review

Keywords: European Union (EU); Energy Economics; Crimea; Black Sea; Diversification Strategy; Russia; Pipelines; Natural Gas; Geopolitics