A look at what victory or defeat would mean for the self-styled Islamic State – and for US objectives in its expanding war in Syria and Iraq.
Turkey says it's unrealistic for it to launch unilateral ground attacks against IS. The US, which is leading an air campaign in Syria, is trying to check the advance of militants against Kurdish forces.
The battle for the Syrian border town of Kobane has pitted Turkey against its NATO allies, which want to see a more robust response to Islamic State's offensive. US-led airstrikes appear to be checking the militants' advance into the town.
If the Syrian border town of Kobane falls, IS will control a long stretch of the Syria-Turkey border, threatening the security of the Kurdish-majority area. US-led airstrikes haven't stopped the advance.
Islamic State forces reportedly have surrounded a Turkish exclave in Syria where the grandfather of the founder of the Ottoman Empire is entombed. Turkey's Parliament is expected Thursday to authorize the deployment of troops to confront IS forces.
Melbourne raids follow a heightened terror alert earlier in September and the tabling of new security laws in Australia's parliament.
Efforts to expand the anti-Islamic State coalition include the debate in Britain's Parliament, deliberations in Denmark and Belgium, and US overtures to Turkey. US and French jets struck IS oil targets overnight in Syria.
Further airstrikes overnight were reported in northern Syria. President Obama will chair a UN Security Council meeting Wednesday to propose new resolution to curb foreign volunteers aiding Islamic State.
The Pentagon said Arab allies assisted overnight strikes in Syria. Islamic State bases were the main target, but the US said it also struck at a separate al-Qaeda affiliate suspected of plotting terror attacks on Western targets.