In an age of 24/7 news coverage, social media and videos going viral, the war in Yemen must rank as one of the most under-reported in recent times, despite a few brave visits by intrepid journalists and film crews.

Yemen can be a remote, difficult and dangerous country to cover, and that is in peace time.

Now, six months after Saudi-led air strikes against Iranian-backed Houthi rebels began on 26 March, the war in Yemen has taken a terrible toll on the Arab world's poorest nation, with both sides accused of committing war crimes and most of the casualties being caused by the aerial bombing.

Long campaign

Six months into this war the situation is not quite a stalemate but both sides do appear increasingly entrenched.

The Houthi rebels, allied with forces loyal to the previous President Ali Abdullah Saleh, still occupy the capital, Sanaa, and much of the more heavily populated north and west of the country.

Fighting them are Yemeni forces loyal to the UN-recognised President Abdrabbuh Mansour Hadi, who has just returned to the second city, Aden, after six months in exile in Saudi Arabia.

These forces are supported by a coalition of 5,000-7,500 Gulf Arab troops led by a Saudi Special Forces commander. They have total air supremacy, having destroyed the Houthi-controlled air force on the ground.

There have been several unsuccessful attempts to broker a peace deal in neighbouring Oman. These have failed over demands that the Houthis withdraw to their northern stronghold and the Houthi demand for more power-sharing and to integrate their forces into a future national army.

Saudi officials have told the BBC that if no deal can be reached soon then Gulf and Yemeni forces will surround Sanaa and overrun it. If the Houthis then chose to stay and fight the death toll amongst civilians would be catastrophic.

The Cost

The statistics are sobering. The UN says that more than 4,800 people have been killed, including more than 450 children, and more than 24,000 people injured.

The majority of casualties have been caused by air strikes, with the Saudi-led coalition being accused by Human Rights Watch (HRW) of using cluster munitions and "indiscriminate bombing of civilian areas". HRW has also accused the Houthis of bombarding residential areas of Aden with mortar and artillery fire as well as laying mines indiscriminately.

The Cost

The statistics are sobering. The UN says that more than 4,800 people have been killed, including more than 450 children, and more than 24,000 people injured.

The majority of casualties have been caused by air strikes, with the Saudi-led coalition being accused by Human Rights Watch (HRW) of using cluster munitions and "indiscriminate bombing of civilian areas". HRW has also accused the Houthis of bombarding residential areas of Aden with mortar and artillery fire as well as laying mines indiscriminately.

Human toll

• Casualties: 4,855 people killed, including 2,112 civilians; 24,971 injured
• Internally displaced: 1.4 million
• Food-aid dependant: 3,518,000

Sources: UN Office for the Coordination of Humanitarian Affairs; World Food Program - 14 September

About 1.4 million people have been displaced from their homes and more than 3.5 million now depend on food aid, yet there is still a partial blockade on the country's ports, imposed by the coalition to prevent any resupply of arms reaching the Houthis.

Many of the Houthi-Saleh arms dumps and military positions have been sited in residential areas, which have resulted in appalling casualties following coalition air strikes.

Unlike Syrians, Yemenis cannot easily flee across their land border as Saudi Arabia has partially completed a 930-mile (1,500km) border fence and reaching distant Oman entails travelling through territory controlled by al-Qaeda.

It is a sign of just how bad things have got in Yemen that many have fled by boat across the Bab al-Mandeb Strait to Somaliland and Djibouti. Some have since returned to Aden, a once thriving Indian Ocean port, now in ruins.

How did it start?

The Saudi-led Operation Firm Resolve began when Saudi warplanes struck Houthi rebel positions deep inside Yemen, taking most of the region by surprise.

Saudi Arabia and its Gulf Arab allies maintain that the conflict really began six months earlier, in September 2014.

The Houthis swept southwards from their mountain heartland and seized control of Sanaa, with the help of the ousted President Saleh, who still commands the loyalty of much of Yemen's military and security forces.

By January 2015 the Houthis had placed the UN-recognised President Hadi under house arrest and by February he had fled to Aden, where Houthi forces very nearly captured him before he was rescued by Saudi Special Forces and smuggled out of the country.

The Houthis say they rebelled because of widespread corruption in government and because Yemen's federal system did not take their interests sufficiently into account.

The Saudis and their Yemeni allies contend that Iran has been arming, training and even directing the Houthi rebels, who are Shia Muslims.

But there has been little evidence of direct Iranian military involvement on the ground. The Houthi advance was enabled largely by renegade forces loyal to the previous president.

Saudi Arabia fears encirclement by Iranian proxies: in Lebanon, Syria, Iraq, and now Yemen.

So, a decision was taken in March by Saudi King Salman and his favourite son, the Defence Minister, Prince Mohammed Bin Salman, to draw a line in the sand and launch this war to show Iran it would not tolerate what they saw as a takeover of their neighbour by an Iranian proxy.

BBC