Since the start of Syria's war in 2011, numerous efforts to halt the conflict through diplomacy have failed.

As the leaders of Iran, Russia and Turkey -- which have become powerbrokers in the conflict -- meet on Syria on Wednesday, here is an overview of previous peace efforts.

A porn star is suing the president. A former Playboy model has apologized to the first lady for sleeping with her husband. The eldest son is divorcing and the scandal-plagued son-in-law's security clearance has been downgraded.

Britain is set to leave the European Union exactly one year from Thursday. Here are some key dates ahead on the path to separation on March 29, 2019:

Egypt's military is conducting a sweeping assault to crush a resilient Islamic State branch in Sinai, but the jihadist group is unlikely to be vanquished quickly, analysts say.

The evacuation of hundreds of rebels and their families from Harasta, a bombed-out town in Syria's Eastern Ghouta, follows a string of similar operations in the seven-year war.

The United States facing defeat in Vietnam. Moscow defied in Czechoslovakia. Student uprisings in Berlin, Paris and Mexico. Fifty years ago the world was rocked by revolt and dashed hopes.

The longstanding relationship between the United States and Saudi Arabia, its main Middle East ally, is founded largely on the exchange of American security for Saudi oil.

Saudi Arabia's crown prince Mohammed bin Salman is set to meet with US President Donald Trump in Washington on Tuesday.

Mutual rival Iran will be high on the agenda, but the 32-year-old strongman prince will also be looking to showcase his sweeping changes to Saudi society and an increasingly assertive foreign policy that includes the war in Yemen and an ongoing diplomatic feud with Qatar.

Russia announced on Saturday the expulsion of 23 British diplomats in a tit-for-tat move following London's response to a nerve agent attack against a Russian former double agent in England.

The Syrian government launched a ferocious assault on a rebel enclave outside Damascus on February 18, saying it wanted to crush Islamist and jihadist groups.