Thai authorities charged Atris Hussein, a Swedish-Lebanese citizen with links to Hezbollah, of planning an attack in Bangkok. He had rented a warehouse and filled it with 3 tons of Urea fertilizer and several gallons of Ammonium Nitrate.
Although the Thai authorities have maintained that Hussein was using Bangkok as a transit, rather than planning an operation there, especially that he bought shipping containers, both the timing and the location highlight what is being planned in Tehran and Beirut's Southern suburbs.
A belated revenge for Mughnieh's death?
First, timing wise, the arrest occurred after the Israelis admitted responsibility (boasted) to the assassination of Iranian scientists and officials, and four years after Iman Mughnieh's assassination. Mughnieh was killed in Damascus on the 12th of February 2008; Hussein was arrested in January with the massive Nitrate stockpile. There is a high possibility that this was an operation to target Israeli and Jewish interests in South East Asia, whether in Bangkok or somewhere nearby.
Was Hussein storing the Nitrate, which is difficult to handle in large quantities, especially for one person, for a February 12 operation? It makes sense that the shipment was made for a short/medium term usage, as handling it is very complex (check this UK guide for instance).
Israel and the Far East
Bangkok is no surprising place for any of Israel's enemies. It is well known that Thailand and Singapore are Israel's main allies in the Far East. Their relations date back to 1956; there is also a visible Israeli presence, mostly intelligence and technology based. There are three synagogues in Bangkok, which has an Israeli embassy since 1996.
I have heard from a PLO official that the Israeli Mossad has a major base in Thailand, and that it uses the country as a platform for high-tech shopping for military purposes in the far-east.
While it is difficult to tell at the moment what exactly they were planning, the timing points towards a Mughnieh revenge attack.