The return of oil from Iran following the landmark nuclear energy deal with world powers could create fresh tensions within OPEC but may reinforce the cartel's output strategy, analysts say.

Tehran and major powers -- Britain, China, France, Germany, Russia and the United States -- clinched a historic agreement in Vienna on Tuesday aimed at ensuring Iran does not obtain a nuclear bomb, and which paves the way for the removal of sanctions and the gradual return of Iranian oil to the global market next year.

The landmark deal on Iran's nuclear program that Russia helped steer through marathon talks is a diplomatic fillip for Moscow which will boost trade with Tehran but could also hit much-needed energy revenues, analysts said.

Iran and the P5+1 group -- Russia, the United States, China, Britain, France and Germany -- struck an agreement on Tuesday that would progressively lift economic sanctions against Tehran in exchange for limitations on its nuclear program.

A close alliance between the U.S.-led coalition battling the Islamic State jihadist group and Syrian Kurdish fighters has racked up successes, but also stirred resentments that could hamper the campaign.

Analysts warn that IS can only be defeated in Syria with support from Sunni Arabs, many of whom are being alienated by what they see as U.S. favoritism towards the Kurdish minority.

Turkey is stepping up its role in the fight against Islamic State extremists after realizing the threats to its own security from jihadists and responding to pressure from its Western partners, analysts say.

Turkish security forces have over the last week arrested dozens of IS militants and sympathizers, in its most significant raids since the group began to seize swathes of neighboring Iraq and Syria in 2014.

The nuclear accord with Iran required a difficult series of compromises for world powers and Tehran.

For President Barack Obama, it meant climbing down from demands that Tehran halt almost all of its enrichment of potential bomb-making material and shutter an underground facility possibly impervious to an air attack. It also meant dropping pledges to secure "anytime, anywhere" inspections and Iran's complete answering of questions related to past weapons work.

Israel has vehemently opposed a nuclear deal with Iran and repeatedly threatened strikes against the Islamic republic, but it must now learn to live with the accord accepted by the world's major powers, analysts say.

Israeli Prime Minister Benjamin Netanyahu evoked frightening scenarios during the months the deal was being negotiated, arguing the agreement would not block Iran's path to nuclear weapons.

When U.S. President Barack Obama accepted the Nobel Peace Prize early in his first term, he acknowledged the controversy surrounding his win by saying he was only at the beginning of his "labors on the world stage."

Nearly six years later, having secured a landmark nuclear deal with Iran, he has achieved a major diplomatic victory that staves off the threat of a military conflict with unforeseeable consequences in an unstable region.

Politicians on the far left and right accused European powers of negotiating with a "gun to the head" of Greece and terrorizing and colonizing it through Monday's new debt deal.

While the leaders of key eurozone countries expressed relief at the proposed deal, parties from Britain's right-wing UKIP to Spain's radical left Podemos said Greece had been stitched up.

Relations between Serbia and Bosnia have remained tenuous since the end of the Bosnian conflict 20 years ago, as underscored by the stone-throwing attack on the Serbian premier at a ceremony Saturday marking the Srebrenica massacre.

Bosnia's 1992-95 inter-ethnic war left 100,000 people dead and around two million homeless, nearly half the country's population at the time.

Like a brush fire kicking up in America's southwest, the storm brought on by Donald Trump's political bombast threatens to scorch all it touches as Republicans brace for fallout from their rival's remarks.

The billionaire tycoon's caustic, seemingly unrehearsed comments about Mexican immigrants, uttered when he launched his White House campaign in mid-June, sparked immigration debates and triggered questions about the braggadocio of a candidate unafraid to disparage fellow Republicans, and whether it hurts the party's chances in 2016.