Tensions rise as Russia, Turkey refuse to back down over jet incident

Russia sent an advanced missile system to Syria on Wednesday to protect its jets operating there and pledged its air force would keep flying missions near Turkish air space, sounding a defiant note after Turkey shot down a Russian fighter jet.

Underscoring the message, Russian forces launched a heavy bombardment against insurgent-held areas in Latakia on Wednesday, near where the jet was downed, rebels and a monitoring group said.

The United States and Europe both urged calm and continued dialogue in telephone conversations with Russian Foreign Minister Sergei Lavrov, a sign of international concern at the prospect of any escalation between the former Cold War enemies.

The downing of the jet on Tuesday was one of the most serious publicly acknowledged clashes between a NATO member and Russia for half a century, and further complicated international efforts to battle Islamic State militants in Syria.

President Tayyip Erdogan made no apology, saying his nation had simply been defending its own security and the "rights of our brothers in Syria". He made clear Turkish policy would not change.

Russian officials expressed fury over Turkey's action and spoke of retaliatory measures that were likely to include curbing travel by Russian tourists to Turkish resorts and some restrictions on trade.

Russian Foreign Minister Sergei Lavrov described it as a planned act and said it would affect efforts towards a political solution in Syria. Moscow would "seriously reconsider" its relations with Ankara, he said.

Jets believed to be Russian also hit a depot for trucks waiting to go through a major rebel-controlled border crossing with Turkey, Bab al-Salam, the head of the crossing said.

Syrian jets have struck the area before, but if confirmed to have been carried out by Russia, it would be one of Moscow's closest air strikes to Turkish soil, targeting a humanitarian corridor into rebel-held Syria and a lifeline for ordinary Syrians crossing to Turkey.