Turkish artillery hit targets near Syria’s Tel Abyad border town for a second day on Thursday, killing several Syrian soldiers according to activists and security sources, after a mortar bomb fired from the area killed five Turkish civilians.Turkey’s government said "aggressive action” against its territory by Syria’s military had become a serious threat to its national security and sought parliamentary approval for the deployment of Turkish troops beyond its borders."Turkey has no interest in a war with Syria. But Turkey is capable of protecting its borders and will retaliate when necessary,” Ibrahim Kalin, a senior adviser to Prime Minister Tayyip Erdogan, said on his Twitter account. "Political, diplomatic initiatives will continue,” he said.In the most serious cross-border escalation of the 18-month uprising in Syria, Turkey hit back after what it called "the last straw” when a mortar hit a residential neighbourhood of the southern border town of Akcakale on Wednesday. The Syrian Observatory for Human Rights said several Syrian soldiers were killed in the Turkish bombardment of a military post near the Syrian town of Tel Abyad, a few miles across the frontier from Akcakale. It did not say how many soldiers died."We know that they have suffered losses,” a Turkish security source told Reuters, without giving further details. NATO said it stood by member-nation Turkey and urged Syria to put an end to "flagrant violations of international law.”The U.S.-led Western military alliance held an urgent late night meeting in Brussels to discuss the matter and in New York, Turkey asked the U.N. Security Council to take the "necessary action” to stop Syrian aggression.