The defence ministers of the North Atlantic Treaty Organization, NATO, have expressed concerns over the “troubling escalation of Russian military activities” in Syria.

The alliance’s Secretary-General, Jens Stoltenberg, said this ahead of talks in Brussels where NATO is expected to assess the development.

Stoltenberg said the alliance is ready to defend all allies in NATO and admits being worried by Russia’s deployment of cruise missiles as well as air strikes.

The NATO representative from Turkey said Russian jets have breached its airspace and demanded Moscow to stop its support for the Syrian leader, Bashar al-Assad.

On claims of targeting opponents of the Syrian leader, the Russian authority has refuted various accusations from the West.

Moscow said its strikes were targeted at Islamic State, ISIS, infrastructure and other militant groups.

The US team had for months been carrying out air strikes against ISIS in both Syria and Iraq but indication are that some countries in the West have given backing to the militants to remove Assad since 2011

Syrian Army Chief of Staff, Gen. Ali Abdullah Ayoub, said on Thursday that the Russian air strikes had weakened ISIS and enabled them to start a “big attack” to reclaim their towns and villages.

According to BBC, the NATO ministers are meeting amid a deepening sense of crisis and are expected to give support to Turkey to manage the escalating crisis among the countries surrounding the sea in northern Europe.