Bahrain hosts counter-terror drills for Arab Gulf nations
Security forces from all six Arab Gulf Cooperation Council (GCC) countries have been carrying out a series of counter-terrorism exercises, codenamed Arab Gulf Security 1.
Hosted by Bahrain, the smallest of the six Gulf Arab states, the country's ministry of interior says the scenarios involve "invasion, rescue and the handling of insurgents".
The GCC comprises Saudi Arabia, Kuwait, Bahrain, Qatar, the United Arab Emirates (UAE) and Oman and the organisers are hoping the drills will lead to a more co-ordinated approach to security in the region.
"The exercise sends a message that the six GCC states support each other against any threat," said Bahrain's Interior Minister, Lt-Gen Rashid Al-Khalifa.
In practice though, the Gulf Arab states have significantly divergent policies towards certain threats and while all are united in their views on counter-terrorism, the level of threat varies widely from country to country.
Saudi Arabia, the regional giant, currently faces the greatest threats.
Its forces are waging a full-scale war in neighbouring Yemen in support of the UN-recognised government there.
While coming under increasing international criticism for the death toll caused by Saudi-led air strikes, Saudi Arabia itself is taking some casualties from missiles fired across its border by Yemen's Houthi rebels.
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Internally, having overcome the threat from al-Qaeda in the mid-2000s, the Saudi leadership is now confronting a number of militant cells linked to so-called Islamic State (IS).
The group's supporters have bombed mosques and targeted security officials. More than 4,000 Saudi nationals are known to have gone to join IS in Syria and Iraq.
There is also simmering discontent amongst the country's sizable Shia minority in the oil-rich Eastern Province.
Demonstrations have turned violent, resulting in arrests, the imprisonment of minors and the controversial execution of a firebrand Shia cleric, Sheikh Nimr Al-Nimr.
Saudi Arabia accuses Iran of stoking sectarian tensions and following the cleric's execution, an Iranian mob sacked the Saudi embassy in Tehran, sparking a rupture in diplomatic relations.
Bahrain is the only Gulf Arab state to have been truly shaken by the so-called Arab Spring protests in 2011.
'Switzerland of the Gulf'
The Sunni monarchy has weathered mass protests by the Shia majority, most of whom protested peacefully in support of more democracy and human rights.
The protests have frequently been marred by an extremely violent minority fighting pitched battles with police and planting homemade bombs indiscriminately.
Despite a number of recent reforms, Bahrain's security forces have been accused of multiple human rights abuses and there have been calls by pressure groups for Britain's Prince Charles to raise these issues during his visit there this month.
The UAE has been the biggest contributor to the Saudi-led coalition fighting in Yemen, drawing on its combat experience in Afghanistan and Kosovo.
Its government faces negligible unrest at home but has arrested dozens of people accused of belonging to the Muslim Brotherhood, an Islamist movement which the leadership sees as a direct challenge to its rule.
Oman has a markedly different foreign policy from its Gulf Arab neighbours, essentially steering a neutral path.
It could perhaps be described as the "Switzerland of the Gulf".
When Iraq's President Saddam Hussein was in power and a local pariah, Oman kept the lines open to Baghdad.
As relations between the Arab Gulf and Iran have deteriorated, Oman has stayed on good terms with Tehran.
And as neighbouring Yemen has descended into a catastrophic civil war Oman has maintained its neutrality, hosting peace talks in Muscat between both sides, so far without success.