The decision by Saudi Arabia and the United Arab Emirates (UAE) to join air strikes in Syria reflects an increasingly muscular foreign policy by the Gulf Arab heavyweights that has already started to reshape the balance of power in the Middle East.
With Egypt, Syria and Iraq - where the Arab world's armed might has usually rested - all now immersed in civil wars or internal political turmoil, the emergence of Gulf states as military players asserting an unremitting hostility to Islamists could alter the region's political equation.
While neither country appears likely to move towards the habitual use of military power to settle disputes or impose interests, the strikes in Syria demonstrated a growing comfort with the use of hard power alongside diplomacy.
“I doubt they would take steps that are wildly out of line with Western policy, such as bombing Iran, but they might act unilaterally in areas that they calculate aren't so important to their Western allies,” said Jane Kinninmont of Chatham House.
Both Saudi and the UAE have given money and backing to Egypt's new rulers since a military takeover last year - ignoring the qualms of long-term ally the United States about the takeover - because they see the country's new president Abdel Fattah al-Sisi as a strong opponent to the Muslim Brotherhood, which they fear has regional aspirations.
That worry has now also prompted the UAE to take a bigger role in Egypt's neighbor Libya, where Washington says the Emirates have intervened in support of militias fighting against Islamist groups. There has been no confirmation of reports that Emirati jets already carried out strikes there.
Both Saudi and the UAE are also applying pressure on Gulf neighbor Qatar blaming it for backing the Brotherhood in Egypt and Islamist groups in Libya. This year the allies, and fellow monarchy Bahrain, pulled out their ambassadors in March, an unprecedented move.
The Saudis are also skittish about neighboring Yemen, where Shi'ite Muslim rebels with ties to Iran have seized the capital and from where al-Qaida's most active regional wing has plotted attacks on the kingdom's ruling family.
Long among the world's biggest defense customers, the Gulf states have amassed lavishly equipped air forces that rival those of any other country in the Middle East.
But their full military capacity has rarely been put to the test. The Saudi and UAE role in the U.S.-led sorties in Syria drew attention because their participation was new at a time when traditional Arab military powers such as Egypt were absent.
They also attracted significant media interest with the details: combatants included a Saudi prince and the UAE's first woman fighter pilot.
That shows the countries have also thought about the positive associations of a more assertive stance that go beyond just addressing a local threat, some said.
“Saudi Arabia and the UAE showed themselves to be closely attuned to the public relations benefits arising from the high-profile participation in military operations by (respectively) a son of the Crown Prince and a female pilot,” said Kristian Coates Ulrichsen, a Research Fellow at Rice University's Baker Institute for Public Policy.
“The Gulf States, at least in the eyes of senior officials in Washington, DC and other capitals, are no longer the counter-revolutionary supporters of a reactionary status quo but critical allies in the new war on terror rapidly taking shape.”
Growing Gulf Arab military confidence also helps to shed old ideas that Gulf armies are unable to play a battlefield role due to limited manpower, said Kinninmont.
“This is an increasingly outdated view that applies only to the traditional boots-on-the-battlefield model of war. The UAE air force is extremely well equipped,” she said.
For both countries however, the decision to abandon an old policy of military caution poses political and security risks.
In Saudi Arabia, which has imprisoned thousands of suspected militants since 2003 and bombarded its people with vociferous attacks on militant ideology, the risk of reprisals from jihadis is clear. The country crushed an uprising from 2003-2006 by al-Qaida militants who accused Riyadh of betraying Muslims for the sake of its alliance with the West.
Riyadh also risks infuriating its Sunni majority by joining Western-led strikes against their fellow members of the sect in Syria and Iraq, whom many Saudis believe are suffering persecution from Shi'ite rulers.
In the UAE, where there is less history of domestic militancy and which has historically been free from attacks, the risks are harder to quantify.
Abu Dhabi and Dubai both have large non-Muslim expatriate populations, enforce a much looser public moral code than Islamists want and boast dozens of major buildings that could attract militant plots.
“There certainly are potential risks involved in this newly assertive UAE foreign policy. Retaliation is one,” said UAE political scientist Abdulkhaleq Abdulla, adding that the other could be divisions among the six Gulf Cooperation Council (GCC) countries.
Nonetheless, fears of allowing Islamist ideology to gain ground in big Arab states in turmoil appear to outweigh any short-term concerns about militant attacks.
“Definitely, we're there (in Syria) not only about IS, we're there against terrorism,” said UAE Minister of State for Foreign Affairs Anwar Gargash in a speech at the U.N. General Assembly.