Rebels are consolidating potentially strategic territorial gains in northern Syria, having seized yet another border crossing into Turkey from already stretched regime forces, experts say. But as they do so, they are heightening tensions with local Syrian Kurdish militia, who are suspected of collaborating with the embattled regime of President Bashar al-Assad and with whom they have already clashed. On Wednesday, after two days of fighting, rebels from the Free Syrian Army (FSA) seized the Tal al-Abyad border crossing. That would give them control of as many as four of the seven posts in the north. Turkish media footage showed the rebel flag hanging from one of the customs buildings on the Syrian side of the border, but an activist said fighting continued through Wednesday night as troops tried to retake the post. Turkey once had close relations with the Assad regime, but now backs the opposition, providing safe haven to rebel forces and allowing men and supplies through the border. \"For a rebellion, it is essential to be able to rely on a border with an allied country to secure the flow of of men, arms and materiel and infiltration and exfiltration,\" a former chief of France\'s intelligence services told AFP. \"This was the case with the Algerian National Liberation Front and the Tunisian border,\" he said about the Algerian war for independence from France. The more territory accessible to a friendly country, the better he said, speaking on condition of anonymity. Also, in terms of political strategy, this serves to show the world that they \"control a large area, which could pave the way for creation of what the international community could consider to be a liberated zone.\" For Fabrice Balanche, a Syria specialist who heads the French research centre GREMMO, the Tal al-Abyad border crossing \"illustrates the rebels\' strategy to conquer the north of Syria.\" The facts that Damascus did not send massive reinforcements and that hundreds of kilometres(miles) along the Turkish border have fallen from the regime\'s grip, \"show that the Syrian government has decided to abandon these small isolated posts, which prove too difficult to defend and supply,\" said Balanche. Tal al-Abyad is about 100 kilometres (63 miles) north of the city of Raqa and was relatively little used until recently. Since late July, rebels fighting Assad\'s regime have seized control of at least three key border crossings with Turkey -- Bab al-Hawa, Al-Salama and Jarabulus. They have also captured crossings on Syria\'s eastern border with Iraq. Both experts agree that the army must now literally \"pick its battles.\" The reasons for that are two-fold: the large number of hot spots proliferating across the country and the army\'s inability to trust all its men, particularly the Sunni Muslims among them. \"The Syrian army must now make choices,\" says the former intelligence chief. \"The border with Turkey is long, and defending it requires a large number of soldiers, who are probably more needed elsewhere.\" One of the goals of the FSA would be to multiply their fronts in order to force the regime to stretch the numbers of troops deployed or to abandon entire regions. \"Since the beginning of the uprising, the army abandoned the Kurdish-majority northeast of Syria to Syrian Kurdish militias,\" said Balanche. \"A few men have remained in the bases across several big cities, but in very little numbers and they do not leave their barracks.\" Some of those militias are close to Turkey\'s separatist Kurdistan Workers\' Party (PKK), which has further estranged Ankara. \"By capturing Tal al-Abyad, the FSA is dangerously approaching the Kurdish-majority regions,\" he said. \"Even if the Kurds are so far... content with controlling their areas, the advance of the FSA will increase tensions. There have already been armed confrontations in which the FSA has lost men.\"