Oil prices have tumbled after Saudi Arabia and its allies cut ties with Qatar, sparking anxiety that OPEC's fragile deal to curtail oil production could come undone. Also and although its daily oil output of around 600,000 barrels represents less than one percent of world crude production, Qatar is a major player in liquefied natural gas. This means that the current deterioration in relations among the Middle East neighbours would have significant implications for oil and gas markets.This paper is novel in its methodological approach, which is used to decompose the variance of oil stock price indices into contributions from country-specific uncertainty and uncertainty common to all countries. The analysis reveals that the contributing factors have varied over time. Prior to the blockade on Qatar, the region-specific uncertainty plays an important role in driving the volatility of oil and gas shares for all cases. In considering the post-boycott, an increasing importance of the country-specific uncertainty factor is shown. This suggests that GCC states that have long resisted making a collective effort to accomplish energy security, are now moving into a new era during which securing their own supply routes will be an indispensable part of their mode of operation. To strengthen energy cooperation, it is first necessary to rebuild trust.