Years of tension between Saudi Arabia and the UAE over Yemen finally boiled over in December when the Saudis accused their ally of arming separatists. The two Gulf powers have clashing visions for regional stability – and that could fracture the entire region.

The Conversation

Saudi-UAE bust-up over Yemen was only a matter of time − and reflects wider rift over vision for the region

Initially, the two gulf states were in alignment over Yemen’s civil war. But the Arab coalition’s unity has long since gone.

If Ukraine gives up land to get a peace deal, eventually reclaiming that land may require Russia's internal collapse. History shows voluntary returns of occupied territory are extremely rare.

The Conversation

Ukraine is under pressure to trade land for peace − if it does, history shows it might not ever get it back

Ukraine may need a major, system-level change or crisis in Russia to regain any lost territories.