Washington - Attacks on Israeli diplomats, new nuclear grandstanding and a glimmer of fresh hope for diplomacy are taking Iran's feud with its Western foes to an unpredictable and possibly more dangerous phase.
A chaotic flurry of events has experts asking whether a tightening sanctions choke hold is beginning to spark volatile behaviour by Iran and a desire to show that any Israeli strikes on its nuclear sites will draw a bloody riposte.
Israel has this week accused Tehran of deploying assassination squads which botched attacks on its diplomats in Thailand, Georgia and India. Iran, seeking to spook the markets, threatened to cut oil exports to six EU nations.
But deepening the intrigue, Iran has also signalled it was ready to return to nuclear talks with world powers, even as it warned it had produced its first 20% enriched uranium and installed another 3 000 nuclear centrifuges.
One explanation circulating in Washington over Iran's apparently contradictory behaviour is that it is seeking political cover, and to project strength, ahead of a return to the negotiating table.
Privately, US officials are sceptical of Iran's claims to new nuclear advances, describing them as "posturing" and essentially meaningless, but suggest they may be another reaction to outside pressure by rulers in Tehran.
Attacks on Israeli diplomats meanwhile could be interpreted as Iran lashing out as payback for covert action widely believed to be the work of Israeli agents which has taken down Iranian nuclear scientists, a US source said.
More ominously, Iran may be also be putting down a marker that it is ready and able, possibly aided by Hezbollah, to strike outside its borders in reprisal for any US or Israeli strike on its nuclear facilities.
Security experts point out that the incidents came close to the fourth anniversary of the killing credited to Israeli agents of Hezbollah commander Imad Mughnieh in Damascus, and may have been intended to show the Iranian-backed group remains dangerous.
Yet such is Iran's isolation and so byzantine are the dynamics between such figures like President Mahmoud Ahmadinejad and supreme leader Ayatollah Ali Khamenei that Tehran's true motives are tough to divine.
US President Barack Obama remarked earlier this month that "knowing who is making decisions at any given time inside of Iran is tough".
One puzzling characteristic about the attacks on Israelis is that they seem somewhat amateurish and hardly worthy of a regime branded by its enemies as one of the world's most prolific sponsors of state terrorism.
In Thailand, an Iranian bomber blew off his own legs. In New Delhi, an Israeli diplomat and her driver were injured but not killed when a motorcycle hitman fixed a magnetic bomb on their car. A similar attack in Tbilisi was thwarted.
Such inefficiency may suggest the attacks were hurried efforts by renegade elements of the Iranian government, or that they are intended as a warning, and not a large-scale affair that could trigger a harsh Israeli response.
"Depending on where you sit, Iran projects different things to different people," said Karim Sadjadpour, of the Carnegie Endowment for International Peace.
"To some, it is an irrational actor whose alleged terror aspirations inspire grave concern, to others it is a rational actor whose bungled terror plots project great incompetence.
"All it takes is one successful hit, however, for that debate to be resolved."
Some US officials believe that Iran's latest belligerence frames its decision to return to the nuclear negotiating table as sanctions bite deep into its economy.
Obama told Iran in his state of the union address last month that despite rising expectations of a military clash, the door remained open to resolving the showdown through diplomacy.
Iran replied on Wednesday, when top negotiator Saeed Jalili told EU foreign policy chief Catherine Ashton in a letter that he was ready for talks.
US officials still do not know whether increasing pressure on Iran means it will be willing to talk about core nuclear issues it has refused to address in the past.
However James Phillips, a Middle East analyst at the Heritage Foundation, said it was likely that Iran saw talks as a chance to stall and to drive wedges in the global coalition opposing its nuclear programme.
"When it appears that the international community is gearing up to ratchet up sanctions on Iran, Iran suddenly comes forward and offers new sets of negotiations," he said.
"When diplomats sit down to talk, they discover that Iran wants to talk about anything except the specific nuclear issues that are to be addressed."