War in the Middle East: Not exactly earth-shattering news in a region which always had more than its fair share of bloodshed.
Still, Saudi Arabia's current military offensive against its neighbour, Yemen, heralds a new and highly dangerous phase in the volatile region: A fight for a new balance of power, one in which Arab countries no longer rely on proxies, but openly attack one another.
Few of those who earlier this decade welcomed the wave of popular revolutions which came to be known by the collective name of the "Arab Spring" could have ever predicted that this supposed period of progress could usher such a dark, violent regression.
Rivalries between Middle Eastern states are not unusual. Some are fuelled by old disputes left unresolved by the old colonial powers of Britain and France: Palestine is the classic case in this category, but there are many others, such as the border disputes between Bahrain and Qatar, or the historic and territorial differences between Syria and Lebanon, or between Iraq and Turkey.
Different ideologies also generated periodic bouts of violence in the region. The pan-Arab revolutions which Egypt's Gamal Abdel Nasser attempted to export during the 1950s and 1960s created mayhem. And then, there is the deep divide between the nations of the Gulf with small populations, but vast oil and gas deposits, and other Arab countries with large populations, but almost no raw materials.
Breaking a taboo
STILL, all the countries of the Middle East continued to pay lip service to the idea of a pan-Arab family in which open violence was unacceptable. So, the traditional way of settling scores between Arab nations was to use proxies. The Palestinians are, of course, the region's veteran proxies, supported and then periodically betrayed by Arab governments, as circumstances demanded.
Other notable proxies were the Kurds, used for decades to settle scores between Middle East nations, or the various tribes which make up Yemen, which were frequently encouraged by outsiders to fight one another: A vicious proxy war between Saudi Arabia and Egypt dominated the 1960s.
Yet on the whole, the taboo against declaring open war against a fellow Arab nation was upheld; Iraqi ruler Saddam Hussein, who broke this taboo by invading Kuwait in 1990, quickly discovered that he faced not only the might of the United States military, but also a united front of virtually all Arab nations.
But over the past few years, this taboo has not only been broken repeatedly, it has also been largely overlooked or forgotten. Jet fighters from Qatar and the United Arab Emirates took part in the Western-led military offensive against the Libyan government of Colonel Muammar Gaddafi in 2011, and Qatar acted as the conduit for the overt supply of weapons to Col Gaddafi's opponents.
Since 2012, most Arab countries have pledged themselves to the overthrow of the government of Mr Bashar al-Assad in Syria, another first development of its kind for the Middle East.
Early this year, Jordanian jets repeatedly bombed terrorist hideouts belonging to the so-called Islamic State in Iraq and Syria on the territory of both Iraq and Syria, without asking permission from either government.
Now, Saudi Arabia, Qatar and the United Arab Emirates are engaged in an air offensive against rebels belonging to the Houthi tribe in Yemen, almost certainly a prelude to an all-out ground offensive in which Egyptian troops may also participate.
One reason for this remarkable but ominous trend is that the wave of revolutions which erupted in the region has weakened the control governments traditionally exercised over their territories, rendering many of the existing borders largely irrelevant.
Fear of Iran
THREE governments claim authority in Libya. In Iraq, the central government exercises no control over large swathes of its territory. Syria is an even bigger domestic mess, with the writ of the government not extending much beyond a belt around the capital. And then, there is Yemen, which has been in continuous turmoil since 2011.
Other Arab states end up being sucked into these disintegrating countries - not so much because they know what they want to promote, but because they know what they wish to avoid.
What worries Arabs most is the growing influence of Iran. A few years ago, the Iranians looked as though they were about to be defeated: Hamas, their Palestinian proxy, was deserting them, Syria's Mr Assad, another Iranian ally, was tottering on the brink of collapse and US-led economic sanctions were biting hard into the Iranian economy.
Now, however, the Iranians seem the biggest winners in the Middle East. They have tightened their stranglehold over Lebanon, succeeded in supporting Mr Assad in Syria, upheld their control over the government in Iraq and opened the way to a negotiated deal with the US, which may end up lifting sanctions.
Iran is also winning in Yemen: The Houthi tribesmen who have taken control over the country are fellow Shi'ite Muslims. Although Teheran denies any connection, Iranian aircraft are now landing daily in Yemen, bringing in weapon supplies and money.
As viewed from Riyadh, the Saudi capital, the desert kingdom is now cornered by Iran from all sides: from Iraq, from an Iranian-fuelled insurgency in Bahrain and from an Iranian-sponsored rebellion in Yemen. "Operation Decisive Storm", as the Saudis now call their attacks on Houthi targets in Yemen, aims to break this perceived Iranian encirclement.
But the biggest reason for this wave of Arab military interventions is the strategic absence of the US from the region. America's steadying hand - Washington's ability to reassure governments either through its military presence or through diplomacy - has largely evaporated. US Secretary of State John Kerry frequently visits the Middle East, but he offers nothing more than advice in a region which needs action.
Paradoxically, the Obama administration's greatest regional preoccupation, that of concluding a deal with Iran, only unsettles the rest of the Middle East - both Arabs and Israel - even further.
THE result is a rising wave of warfare, with ominous consequences for the future. The more Arab countries intervene in one another's affairs, the more unruly the region will become. Like in Afghanistan, the crisis in Yemen has no military solution, but the Saudis and their Egyptian allies will insist on trying to provide one.
The result may well be a war that goes on for a decade and still doesn't clip Iran's wings as the Saudis want, largely because Iran can continue supplying the Houthis at little cost to itself. The more Arab nations intervene in Iraq, the more the Iraqi state would be doomed to disintegration. And the less borders are respected, the larger the potential for the real doomsday scenario for the region - a broader and bloodier confrontation between Sunni and Shi'ite Muslims.
A good case can be made that the old proxy wars of the Middle East were not very pleasant either. But proxy wars are easier to end or at least easier to handle than open interventions where the pride of governments and politicians is at stake, and compromises are, therefore, more difficult to arrive at.
The Saudi military intervention in Yemen is directed by the new Saudi king and by the kingdom's new defence minister, Prince Muhammad bin Salman, the 35-year-old favourite son of the monarch, a man with no military experience and just two months into the job. Neither can risk admitting to a possible military failure so, once launched, the Saudi operation in Yemen will continue regardless of the consequences.
In short, the Middle East's new way of warfare is likely to be both more prolonged and bloodier than past confrontations.
For decades, Western strategic experts and armchair strategists frequently castigated the US for its involvement in the Middle East. But as current developments in the Arab world indicate, there is cause to regret its absence as a huge new wave of instability sweeps the region.