A devastating attack by a pair of suicide bombers in Beirut on Tuesday blew off the front of Iran's embassy, killing at least 23 people and moving the front lines of the deadly civil war in Syria to the centre of Lebanon.
The Abdullah Azzam Brigades, a Lebanon-based al-Qaeda-linked group, claimed responsibility for the twin attacks and threatened further assaults unless Iranian and Hezbollah forces are withdrawn from Syria where they have helped prop up the regime of Bashar al-Assad.
The bombing came on the eve of continued talks between world powers and Iran over that country's disputed nuclear program. The two sides had come tantalizingly close to an interim deal two weeks ago in Geneva but adjourned after a last-minute disagreement.
The proposed arrangement would have had Iran halt parts of its program of nuclear development in exchange for a six-month lifting of some of the international sanctions imposed on Tehran. The sanctions were adopted after Iran failed to comply with Security Council resolutions that it halt uranium enrichment that could be used to make weapons.
Two issues apparently blocked the deal from being consummated: an omission of any reference to Iran's right to enrich uranium, and a halt to construction at a controversial heavy-water production facility in Arak, southwest of Tehran. Iranian negotiators rejected the wording on both subjects.
Tehran accuses the five permanent members of the Security Council and Germany (the P5+1 group) of making changes just before the end of the three-day meeting after the parties had agreed on an earlier text. Iranian officials suggest Israeli pressure was responsible for the changes.
Certainly the revised wording appeals more to Israel than did the earlier wording.
"The original clause on Arak … is Iran's [negotiating] tactic in a nutshell," said Emily Landau, a senior research associate at the Institute for National Security Studies in Israel, who was briefed on the contents of the deal. It agrees "to make concessions that are not concessions at all."
The original text would have prevented Iran from commissioning the Arak facility for six months, Dr. Landau says, but would have allowed Iran to continue constructing the facility.
The trouble is, she noted, "Iran wasn't on track to commission the facility in the next six months." What Iran really wanted was to continue the construction, she said. As well, it would have had some sanctions lifted in exchange for a meaningless promise not to commission the facility for six months.
"I hope we'll be able to convince our friends this week and in the following days to get a much better deal," said Israeli Prime Minister Benjamin Netanyahu as he met with French President François Hollande Monday in Israel. "It can be achieved."
In Washington last week, Israel's Economy Minister Naftali Bennett urged U.S. lawmakers to impose further sanctions on Iran rather than lift existing ones that brought Iran to the negotiating table.
Mr. Bennett, leader of the extreme right Jewish Home Party, likened Iran to a boxer knocked down for the count when a U.S. referee stops the count at eight. Why, Mr. Bennett asked, should we help Iran to its feet just as we are about to win the match?
U.S. President Barack Obama has countered with arguments of his own. The relief from sanctions offered to Iran, he says, are "limited, temporary and reversible." They also are essential, the administration adds, if Iran's new leaders are to show a doubting Iranian public that their country will get something tangible from a final agreement.
On Tuesday, Mr. Obama met with leading members of the Senate and asked them to hold off on tightening sanctions in order to give diplomacy more time to reach an agreement.
Senator Bob Corker, the ranking Republican on the Foreign Relations Committee, reserved his judgment but said voting on new sanctions would not likely take place until next month.
For its part, Iran has waived its demand for formal language acknowledging it has a right to enrich uranium.
Iranian Foreign Minister Mohammad Zarif said his country was not abandoning the right, only that it does "not see any need for it to be recognized by others, since it is an integral part of Iran's rights under the Non-Proliferation Treaty." Whether integral or not, the concession may improve the chances of a deal being made.
For the people of Lebanon, a nuclear agreement between the world powers and Iran took on new significance with Tuesday's bombing.
The threat to Lebanon will end only when peace returns to Syria, and peace can only be achieved with Iranian participation, notes Scott Field, a visiting scholar in the Institute of International Studies at the University of California at Berkeley.
Iran may well conclude that its ally Mr. al-Assad needs to go, Mr. Field said, "but it is exceedingly unlikely to take the risky steps necessary to act on that conclusion until it has secured a nuclear deal."