AP

BANGKOK IT began when three men blew up their house accidentally on Valentine’s Day in Bangkok. It ended with a gory scene that looked more like Baghdad: A bloodied, wouldbe bomber with severed legs moaning on a glass-strewn sidewalk after another botched blast.

Last week’s explosions in the Thai capital announced the apparent arrival of international terrorists in this Southeast Asian nation, revealing a plot allegedly aimed against Israeli diplomats.

But big questions remain about who was behind the plot, and why.

So far, three Iranian citizens have been detained in the case, though police say they haven’t revealed anything substantial under interrogation.

A Thai court issued an arrest warrant for an additional Iranian suspect this week, and on Tuesday, police were investigating the discovery of stickers plastered on Bangkok utility poles and billboards that may have marked routes for intended victims.

Was it part of a covert titfor- tat war in which Iranians are hitting back at Israel for allegedly killing Iranian nuclear scientists in Tehran? Were the assailants part of a global terror network? If they were professional assassins, why were they so inept? “There are many theories,” government spokeswoman Thitima Chaisaeng said shortly after the Bangkok blasts.

And so far, not many answers.

The explosions Feb. 14 came one day after two other incidents in India and the former Soviet Republic of Georgia in which bombers tried to hit Israeli targets with so-called “sticky” bombs that attach magnetically to vehicles.

Whoever was responsible for the cross-continental string of violence, the perception that Tehran is to blame “has undoubtedly exacerbated the already mounting tensions surrounding Iran’s nuclear program, and international efforts to curtail it,” said Will Hartley, head of the Terrorism & Insurgency Center at IHS Jane’s in London.

Iran has denied responsibility.

Thai investigators, meanwhile, have been left to pick up the pieces and solve the riddle of what happened on Thai soil.

Police say a 31-year-old Iranian named Leila Rohani, who visited Thailand four times over the last year, paved the way for the operation by renting a two-story house in the Thai capital.

Rohani left Thailand on Feb. 5, and the three nowdetained Iranians arrived in the predominantly Buddhist country several days later, each traveling on a 60-day tourist visa. The trio met in Pattaya, a beach town on the Gulf of Thailand known for its go-go bars.

They included Mohammad Kharzei, 42; Masoud Sedaghatzadeh, 31; and Saeid Moradi, 28. Immigration police say Kharzei and Sedaghatzadeh, at least, had visited Thailand before, Sedaghatzadeh as recently as December.