Ukraine’s state energy firm Naftogaz and Russian gas giant Gazprom agreed to continue working on options for continuing the transit through Ukraine, a senior Naftogaz official said. Yuriy Vitrenko said on Facebook that it was too early to talk about a draft agreement. The current transit deal expires at the end of this year, according to Reuters.

Geopolitical tensions between Russia and Ukraine, a U.S. challenge to Russia’s dominance in European energy markets and incomplete gas pipelines are just some of the issues complicating a gas transit deal between Kiev And Moscow’s energy giants that needs to be signed before the end of 2019.

Ukraine and Russia are involved in an unresolved territorial conflict that has run for over five years but on the energy front, in the meantime, Russian gas has still traveled through its main route of Ukraine to reach Europe, according to CNBC.

A 10-year gas transit deal that has kept Europe supplied with Russian gas is about to expire on December 31.