VIENNA -- Joint efforts by U.S. Secretary of State John Kerry and three other Western foreign ministers failed Sunday to advance faltering nuclear talks with Iran, with the target date for a deal only a week away.
"There has been no breakthrough today," said British Foreign Secretary William Hague after meetings with Mr. Kerry and the foreign ministers of France, Germany and Iran.
The trip gave Mr. Kerry a chance to ease an espionage dispute with Germany. After meeting with German Foreign Minister Frank-Walter Steinmeier, both stressed the importance of their cooperation in solving global crises, yet offered little indication they have fully mended ties.
Separately, Mr. Kerry spoke by telephone with Israeli Prime Minister Benjamin Netanyahu about the escalating Middle East violence. Like the others, he also met with Iranian Foreign Minister Mohammad Javad Zarif.
"We're working, we're working; we just got here," said Mr. Kerry, chiding reporters asking about progress as Sunday's meetings wound down.
But the dispute over Iran's enrichment program appeared to be defying the Western foreign ministers' combined diplomatic muscle.
Tehran says it needs to expand enrichment to make reactor fuel, but the U.S. fears Tehran could steer the activity toward manufacturing the core of nuclear missiles. The U.S. wants deep enrichment cuts; Iran wants to greatly expand enrichment.
"There is a huge gap" over enrichment, said Mr. Hague, in comments echoed by the other foreign ministers.
Mr. Steinmeier and French Foreign Minister Laurent Fabius left Sunday, a few hours after they arrived.
Mr. Kerry and Mr. Hague stayed on for another day of diplomacy. Still, the dispute and other differences strongly indicated that six world powers and Tehran will need to continue negotiations until next Sunday and could decide to extend their talks past that informal deadline for a deal.
Such an agreement would buy time to negotiate a pact limiting the scope of such programs in exchange for a full end to nuclear-related sanctions against Tehran.
"Obviously we have some very significant gaps still, so we need to see if we can make some progress," Mr. Kerry told reporters before a meeting with Catherine Ashton, European Union foreign policy chief, who is convening the talks.
"It is vital to make certain that Iran is not going to develop nuclear weapons, that their program is peaceful. That's what we are here trying to achieve."
Lower-ranking officials represented both Russia and China, possibly reflecting their view even before Sunday that talks past next Sunday are unavoidable.
Mr. Kerry arrived in Vienna after a diplomatic bounce in Afghanistan, where he persuaded rival presidential candidates to agree to a full audit of their recent runoff election. They also agreed to a power-sharing arrangement.
But the nuclear dispute could prove harder to solve.
Iranian hardliners oppose almost any concession by moderate President Hassan Rouhani's government. In the U.S., Republicans and Democrats have threatened to scuttle any emerging agreement because it would allow Iran to maintain some enrichment capacity.
Outside the negotiation, regional rivals of Iran -- including Israel and Saudi Arabia -- are extremely skeptical of any arrangement they feel would allow the Islamic republic to escape international pressure while moving closer to the nuclear club.
An interim deal in January effectively froze Iran's program, with world powers providing sanctions relief to Tehran of about $7 billion. The two sides also agreed to a six-month extension past July 20 for negotiations to reach a comprehensive deal if necessary.
Mr. Kerry did not directly address German-U.S. tensions caused by revelations about widespread American spying in Germany. "We are great friends," he told reporters, extolling the "enormous" importance of cooperation on the world stage between Washington and Berlin.
Mr. Steinmeier was more direct. Calling good bilateral relations "indispensable," he acknowledged recent "difficulties" and urged that relations "revive on the basis of trust and mutual respect."