(CNN)Five of CNN's correspondents gathered recently to discuss how the world changed in 2015 and what may come in the year ahead. Nick Paton Walsh, Nima Elbagir, Ivan Watson, Clarissa Ward and Arwa Damon sat down with videographer Claudia Morales and talked about the stories, issues and people they had covered. See their conversations in a series of videos and catch up on the key stories of our time. Here, Russia. Also in the series: ISIS; the refugee crisis
Russia: What happened in 2015 and what's ahead
Last winter the war in eastern Ukraine raged. Then, after Russian-backed forces captured a key railway junction, the fighting went into abeyance, held together by a Western-backed ceasefire. Now, the focus of Russian President Vladimir Putin's foreign policy is Syria.
As ISIS continued its rise in Syria and Iraq, and demonstrated a growing ability to inspire or even orchestrate attacks in Europe and North Africa, so Putin spotted an opportunity. In one move, he could make a serious military commitment to a long-standing Russian ally and expose the dithering of the West and its concomitant fear of another disastrous military endeavor abroad.
Russian airstrikes appear to have led to gains on the ground for Syrian government forces. On the diplomatic front, Western powers have been edging away from their previous hardline position on Syrian leader Bashar al-Assad. Now some in the West say they can envisage some sort of transitional role for Assad in a post-conflict Syria.
Even those events that could have caused a wobble have been turned to Russia's advantage. When Turkey shot down a Russian bomber it was an awkward moment. Moscow and Ankara have been close, with trade, investment and tourism all serving to cement strong ties.
But the strike offered Putin the chance to pursue one of his overarching foreign policy goals: the weakening of NATO. If Turkey had failed to follow alliance protocol in the course of its military action, Putin seemed to suggest, then the Western alliance was hardly fit for purpose. Another sign of American weakness.
Putin knows he can't crush the West over Ukraine or over Syria. But he doesn't want to; what the Kremlin wants abroad is weakness and division. A divided Ukraine will go nowhere fast; it certainly won't be joining NATO or the EU anytime soon. A weak America poses less of a threat in itself and less of an ideal for other countries to rally round.
The challenge for the year ahead is whether Putin can reach an accommodation with the West over Syria so all the world's main powers are pulling in the same direction, without Russia feeling like it is a docile follower rather than a muscular leader.