World Bulletin / News Desk

NATO defense ministers gathered in Brussels on Thursday to discuss the challenges the alliance is facing on both its northern and southern flanks.

Addressing the meeting on Thursday at NATO headquarters, Secretary-General Jens Stoltenberg said: "All around us, we see significant challenges: The crisis in Ukraine; failed and failing states in North Africa and in the Middle East; the spread of terrorism."

The meeting comes days after a Russian warplane violated Turkish airspace on its border with Syria over the weekend. Moscow indicated Monday that its fighter jet violated Turkish air space due to "bad weather conditions".

"And the situation [is] now complicated further by Russia’s military actions in Syria. As well as the largest refugee crisis in Europe since the Second World War," Stoltenberg added.

Russia began flying combat missions over Syria on Sept. 30 following an escalation in its military support for President Bashar al-Assad’s regime. Despite Russia claiming to be targeting ISIL, the U.S. and its allies have complained about Russian airstrikes on “moderate” forces fighting Assad.

-UK to deploy forces in Eastern Europe

Meanwhile, Britain confirmed it is to deploy troops on NATO’s eastern flank as “reassurance” for Poland and the Baltic countries against Russia.

U.K. Defense Secretary Michael Fallon said “a small number” of UK military personnel – thought to be around 100 – would be sent to Estonia, Latvia and Lithuania, as well as Poland.

Speaking as he arrived today's Brussels meeting, Fallon said: “This is further reassurance for our allies on the eastern flank of NATO – for the Baltic states and for Poland.

“That is part of our more persistent presence on the eastern side of NATO to respond to any further provocation and aggression.”

A Ministry of Defence spokeswoman confirmed the planned deployment but told Anadolu Agency that Fallon’s comments stood for themselves and they would not be adding anything further.