By Chris Hogg
BBC News, Tokyo
Will three anti-whaling activists from the UK and US end up standing trial in Tokyo?
The activists are accused of endangering the Kaiko Maru (top)
Japan is attempting to press charges against activists for the first time since 2000, when protesters started harassing the Japanese whaling fleet in earnest.
Earlier this week Tokyo's Metropolitan Police Department obtained arrest warrants for the three men: Daniel Bebawi from Nottingham, the UK, and Americans Jon Batchelor and Ralph Koo.
Police sources in Tokyo accuse the men - members of the Sea Shepherd Conservation Society, an anti-whaling group - of approaching a Japanese whaling ship, the Kaiko Maru, and laying a rope in its path in an effort to foul its propeller in February last year.
The men are also alleged to have thrown smoke bombs onto the ship which started a fire.
'Red notice' sought
Unconfirmed reports here say Japan's National Police Agency has now approached Interpol and asked them to place the men on their "wanted" list.
They want the international police agency to issue a "red notice" which would notify the authorities in Britain and the United States that a national arrest warrant had been issued for these men.
Only a very small proportion of Interpol's "red notices" are made public. The country making the request, in this case Japan, can ask for the matter to be kept out of the public eye.
The first Mr Bebawi might know of it might be when British police turn up to arrest him.
Interpol cannot insist that the British authorities use a "red notice" as a basis for a provisional arrest. Some countries do, some don't.
Whether or not they do depends on the links between the country seeking the arrest and the country required to carry it out. It can also depend on the seriousness of the crime.
Japan and the UK do not have an extradition treaty. But that does not necessarily preclude the prospect of extradition, according to a British Embassy spokesman in Tokyo.
The war between whalers and activists has heated up over recent years
"Any extradition request received from a 'non-treaty' partner would be considered on a case-by-case basis," he said. "For a case to be considered the offence... must be an offence in the UK."
The extradition treaty that exists between the US and Japan lists the offences which are extraditable. These include offences related to disruption of shipping vessels.
They are also for the first time suggesting that the activists may have committed a crime under a UN convention, "The Convention for the Suppression of Unlawful Acts of Violence Against the Safety of Maritime Navigation".
This could make the activists liable for arrest in countries that are signatories to the convention.
Japan appears to be taking a tougher line against those who seek to disrupt its whale hunt than it has in the past.
So what has changed?
First, there are those in the Japanese parliament and media who have accused the Japanese whaling fleet and its operator of being "wimps" in the face of the attacks by the Sea Shepherd Conservation Society. Japan should not tolerate this kind of humiliation, they argue.
Japan may also feel more confident now that the group has alienated many in the anti-whaling camp with its direct action against the whalers.
Activists vow that the new tactics will not scare them off
Professor Jeff Kingston from Temple University in Tokyo believes that Japan has been losing in the court of public opinion over its whaling programme.
"It clearly wants to persist with this programme and is seeking to deter other activists from disrupting its hunts," he says.
"Sticking Interpol on the activists is unlikely to deter committed anti-whaling campaigners," he adds. "But it may lead to some shifts in tactics."
Captain Paul Watson who has led the Sea Shepherd actions against the Japanese fleet has already described these legal moves by Japan as "absurd" and made clear it will not deter his organisation from stepping up its efforts against the whalers.
Others caution that increased publicity can only benefit the activists.
Japan has raised the stakes it seems - but can it afford to pay the price if its tactics go wrong?