Turkey's main militant Kurdish group, the PKK, says it has called off a unilateral ceasefire with the Turkish Government in protest at what it says is Ankara's failure to grant Kurds greater political and cultural rights.
The group, now renamed Kadek, says it does not believe that there would be a return to all-out war - an apparent reference to its 15-year separatist conflict with Ankara in which more 30,000 people died.
But a spokeswoman said there could be a resumption of what she described as "low intensity warfare".
A return to all-out confrontation seems unlikely
Four years ago this week, a senior PKK commander, Osman Ocalan, said the movement was complying with its imprisoned leader's order to observe a ceasefire and withdraw its forces from Turkey.
The PKK, he said, would never again take part in an armed struggle.
The group said it would concentrate instead on establishing a political process to win improved political and cultural rights for Turkey's Kurdish minority.
Things have moved on significantly since then. Over the past year, in particular, Turkey has introduced some fundamental reforms on Kurdish cultural rights, many of them linked to Ankara's long- term bid to join the European Union.
The Turkish parliament recently adopted an impressive raft of EU-inspired reforms, including measures which would pave the way for Kurdish language education and broadcasting.
It has also offered PKK members a partial amnesty, although the group's leaders and military commanders were explicitly excluded from this offer. Such measures would have been unthinkable in Turkey only a few years ago.
But as far as the PKK is concerned, this is still not enough.
Mizgin Sen, Kadek's European spokeswoman told the BBC: "Taking decisions is one thing, implementing is another."
The EU has already made it clear that it is waiting to see how Ankara implements these reforms. Now, it will also be watching carefully to see what happens on the ground in largely Kurdish south-eastern Turkey.
Meanwhile, the Turkish Government is continuing to do all it can to persuade sceptics in the EU that it will be ready to start accession talks by the end of 2004.
So far, Ankara's reaction to the PKK/Kadek statement has been low-key. Turkey's Foreign Minister, Abdullah Gul, on an official visit to Europe, shrugged off the statement.
"The terror group's shouting in recent days" he said " is the result of panic stemming from the partial amnesty law."
So how realistic are the group's threats? The PKK/ Kadek has suggested that it could re-instate the ceasefire by December, if the Turkish Government responds with its own ceasefire.
Certainly, any indication that the PKK intended to relaunch its military activities would ring alarm bells in Washington
That's not very likely; Turkey has traditionally refused to negotiate with the PKK, which it regards as a terrorist organisation.
Meanwhile, analysts like Michiel Leezenberg of Amsterdam University believe that the Kurdish organisation is militarily much weaker than it was at the height of the conflict in the 1990s. Mr Leezenberg says that he doubts whether the group could now produce anything more than what he described as "nuisance value".
Nevertheless, he believes that by making this announcement, the group is trying to send some political signals.
"They want to suggest that Turkey cannot become an EU member before the Kurdish question has a political solution " he said.
"Towards America, they signal that they are still very much part of the game and Northern Iraq cannot be peacefully settled unless a political settlement for the PKK is going on."
Certainly, any indication that the PKK intended to relaunch its military activities would ring alarm bells in Washington.
Several thousand PKK fighters are still based in northern Iraq.
Turkey has been pressing the US to take action against these bases. Washington, pre-occupied with security problems in other parts of Iraq, will be anxious to avoid any new problems breaking out in the relatively peaceful North.
The PKK is also likely to want to avoid any confrontation with the powerful US.
However, the group's leaders may be hoping that their latest statement could prompt Washington to put pressure on Ankara to extend its existing amnesty, or offer other concessions to Turkey's Kurds.