Aghast at Iran's Syria gains, Gulf Arabs see potential in Trump

(Repeats story from Tuesday)

* Riyadh determined to target Iranian influence

* Gulf Arab relief aid will continue

* Military support appears in question

* Trump's anti-Iran stance cheers Gulf Arabs

* Discreet talks with Trump associates

* Syrian negotiator hopeful of Trump

By William Maclean

RIYADH, Dec 20 (Reuters) - "Where are you, Oh Arabs, Oh Muslims, while we are being slaughtered?"

An old man's cry, in a video posted online from Aleppo's ruins, poses an uncomfortable question for the mainly Sunni Muslim Arab states backing rebels fighting President Bashar al-Assad and his allies Iran and Russia.

For Saudi Arabia, locked in a regional struggle with Iran, Assad's capture of the rebel haven reflects a dangerous tilt in the Middle East balance of power towards Tehran.

Dismayed by this boost to Iranian ambitions for a "Shi'ite crescent" of influence from Afghanistan to the Mediterranean, Riyadh is determined to reverse Tehran's gains sooner or later.

Countering Iran, buoyed by its 2015 nuclear deal with world powers, remains central to Gulf Arab policy but it is not clear how this might be achieved, especially when other concerns are multiplying.

Beset by low oil prices, at war in Yemen, and ties with Egypt strained, Riyadh and Gulf allies are questioning how much armed help they should now give the rebels, diplomats say.

The monarchies are frustrated with President Barack Obama's light touch approach to the war - relying on local fighters instead of large U.S. military deployments or missile strikes.

President-elect Donald Trump poses an intriguing contrast.

"MAKE A DEAL"

Seen as more decisive than Obama, Trump's choices of James Mattis, a retired Marine general distrustful of Iran, as Defense Secretary, and oil man Rex Tillerson as Secretary of State, have pleased Gulf Arab energy exporters.

But much remains uncertain, not least Trump's admiration for Russian President Vladimir Putin, an Assad ally.

"What we have learned from the U.S. election is to wait for actions, not words," said former Saudi intelligence chief Prince Turki al-Faisal.

A senior Western diplomat said Saudi officials were curious to see how Trump translates into policy his campaign criticism of Iran and his praise of Putin.

Saudi Foreign Minister Adel al-Jubeir said he had spent time in the United States to sound out the next administration.

Officials said Gulf states were asking Trump associates about Syria, to assess whether he would pursue a U.S.-led effort with Gulf states, Turkey and Western nations to arm the rebels.

Trump has indicated he may abandon the rebels to focus on fighting Islamic State.