BANGKOK/LONDON The loudest noise that Thongma Danoi had ever heard was followed 20 minutes later by the strangest sight: a dazed and bloodied Iranian carrying two wire-adorned devices through the usually sleepy Bangkok neighborhood.
"He was losing a lot of blood," said Thongma, 68, who saw the Iranian man, later identified as Saeid Moradi, fleeing a rented house blown apart by a massive explosion on Tuesday. "People were shouting, 'He's got a bomb!' I tried not to look at him."
Minutes later, he heard another explosion, as 28-year-old Moradi reportedly threw a second bomb at a taxi that wouldn't pick him up. His rampage ended nearby, outside a school, with a third explosion that ripped off one of the bomber's legs and damaged the other so badly it had to be amputated.
Israel said the Bangkok blasts were evidence of an "attempted terrorist attack" and blamed Iran. Tehran denied involvement.
As bombings go, this week's trio of apparent attempted attacks on Israeli targets -- which also included an attack on a car carrying the wife of an Israeli diplomat in New Delhi and a bomb found attached to an Israeli diplomatic vehicle in the Georgian capital Tbilisi -- seemed unusually inept.
But security experts believe they sent a clear message, the first serious retaliation for a quietly waged but increasingly bloody campaign of sabotage waged against Iran's nuclear program.
At least four Iranian nuclear scientists have been killed in recent years in attacks believed to have been carried out by or for Israel's intelligence services. While Israel invariably refuses to comment, some security analysts also suspect it has been involved in a string of major explosions at military and nuclear facilities in Iran, such as one in November that killed more than a dozen, including a senior Iranian general.
Tehran denied any involvement in this week's attacks, accusing Israel of staging them itself. But there are widespread suspicions that the real intent may have been to warn the Jewish state that Iran is prepared to retaliate in kind.
"I see in what happened a message to the effect of: 'Anything you can do, I can do too,'" said Gad Shimron, a former Mossad field officer who writes on intelligence matters. "In other words, if Israel uses terror for its security needs, it can expect reprisals from the other side."
In an environment of growing tension, paranoia and fear, there is a risk of escalation fuelled by worries over Iran's nuclear program, a potential Israeli strike on Iran and a devastating wider conflict in the Gulf.
"There is more and more pressure on all sides," says Anthony Cordesman, a former senior U.S. intelligence and defense official and now chair of strategy at the Center for Strategic and International Studies, the Washington D.C.-based think tank. "All of them are interacting now in ways that make it harder and harder to anticipate the actions of each other."
MIRROR IMAGE ATTACK
While some Western officials say it is too soon to blame Tehran for this week's attacks, security analysts point to growing circumstantial evidence. Thai authorities said similar magnetic bombs were used in New Delhi, Tbilisi and Bangkok.
While they did not blame Iran directly, they said the two other men arrested in relation to the Bangkok blasts -- one in the Thai capital and the other in Kuala Lumpur airport in Malaysia as he bought a ticket to Tehran after fleeing Thailand -- were also Iranian.
The attack in Delhi -- in which a motorcycle attacker attached a magnetic or "sticky" bomb about the size of an iPad to an Israeli diplomatic vehicle -- appeared to be a virtual mirror image of the lethal January 11 attack on Iranian scientist Mostafa Ahmadi-Roshan in Tehran traffic.
Indian police say they have yet to track down the young man in a leather jacket riding a red motorcycle who eyewitnesses said attached the device before racing away. But they said they were investigating phone calls made to foreign numbers from the immediate area just after the attack, particularly four calls made to Iran, Lebanon and Pakistan.
Tal Yehoshua-Koren, the wife of Israel's defense attache to Delhi was injured in the attack. If the bomber had attached the device to the side of the car with the petrol tank, its occupants would have been less likely to survive, police said.
Iran has long used proxy groups such as Lebanon's Hezbollah and Hamas in the Palestinian territories to attack its enemies overseas, and intelligence experts believe they may have done so again in this case. Tehran's relationship with Hamas has frayed in recent years, but Iran remains close to Hezbollah.
Other analysts believe the culprits may be members of Tehran's hardline Revolutionary Guard, perhaps from the Quds Force, believed responsible for "extraterritorial operations".
Conspiracy theories are rife . Some even point to the possibility that Israel itself might have orchestrated the attacks to damage Iran's relationship with key Asian powers particularly India, a current main purchaser of Iran's oil.
"The situation is getting worse and worse and it of course provides a good excuse for anyone who wishes to engage in real hostilities," said Farhang Jahanpour of Oxford University's Faculty of Oriental Studies.
SHADOWY PROXY GROUPS
For most analysts, however, these attacks plus an alleged plot last year to kill the Saudi ambassador to the United States -- which U.S. authorities say they thwarted -- suggest Iran is now taking new risks or has signaled its proxies may do so.
"We are now seeing evidence of Iranian willingness to go after foreign targets in a way that has not been that much in evidence before," says Nigel Inkster, a former deputy chief of Britain's Secret Intelligence Service (MI6), now at London's International Institute for Strategic Studies.
"Whether we're talking about the Iranians themselves or proxies such as Hezbollah, it is very difficult to know. It's also not clear whether they are acting on direction from the top or have simply been given the impression they (now) have greater flexibility."
The relative ineptitude of the attacks suggests Tehran wanted to send a message rather than inflict heavy casualties.
"The Iranians aren't interested in a truck-bomb-level attack on an Israeli embassy because that could provoke a conflict," said Paul Quaglia, director of security consultancy PSA Asia and a 20-year veteran of the Central Intelligence Agency.
"But they're upset about having ... nuclear scientists hit. Farming out these low-level bomb attacks against diplomats is the next best thing."
Israel too is also suspected of using a range of shadowy local resistance groups in Iran. Some of their members may not be aware of who they are ultimately working for, a technique known as "false flagging".
Several reports suggest Israeli agents may have impersonated their US counterparts in recruiting or directing members of the People's Mujahideen of Iran -- often known by its initials MEK -- or Jundallah, a group sometimes linked to al Qaeda that is based largely in the province of Baluchistan.
"There is some evidence that this has been happening," said former MI6 deputy chief Inkster. "It may be one of the things that has soured the relationship between Israel and the US. The "false flag" issue always makes things more complicated."
LESSONS OF HISTORY
The United States denies any involvement in the lethal attacks within Iran -- even issuing a rare condemnation of the January car bomb killing.
One Gulf security source told Reuters he believed U.S. agencies were directly involved in some attacks, working alongside MEK. U.S. officials have denied such suggestions, saying they would never work with the resistance groups partly because they were suspected to have been infiltrated by Iranian intelligence.
Former and serving U.S. and other Western officials say the CIA does not have the authorization -- or "finding" -- from the White House to conduct lethal attacks within Iran, although few doubt they are involved in a wide range of other intelligence operations.
While the emerging "shadow war" might escalate in the months to come, not everyone believes it heightens the risk of a wider conflict that the United States, Iran and Israel are keen to avoid.
But the lesson of history -- particularly 1914, when the assassination of Austrian Archduke Franz Ferdinand in a Sarajevo sidestreet sparked a world war -- is that mistakes can happen.
"Everyone here is used to playing the long game," says former U.S. official Cordesman, saying he believed outright war was still likely to be avoided. "But you can still have someone on a street corner in the middle of nowhere... who sparks something that changes the course of history." (Additional reporting by Dan Williams in Jerusalem, Mark Hosenball and William Maclean in London, Sinsiri Tiwutanond in Bangkok, John Chalmers and Satarupa Battacharjya in New Delhi)
(Reporting By Peter Apps, editing by Rosalind Russell)