Soldiers have been deployed in the Thai capital, Bangkok, amid deadlock over the long-running anti-government red-shirt protests.
The military says it is prepared to take "decisive action" to disperse the protesters, who are camped out in the city centre.
But the red-shirts, who have occupied key parts of Bangkok for more than five weeks, have vowed not to back down unless the government is dissolved.
The thousands of protesters have constructed barricades across some of Bangkok's main thoroughfares to fortify areas they have occupied.
Some have also been stockpiling stones and sharpened bamboo poles in case of violence - the army has said it will respond with live ammunition if attacked.
Army officials also said they would use tear gas to push protesters back, prompting some to create improvised protection for themselves.
Observers said some of the protesters appeared to be disabling security cameras watching over their encampments.
The red-shirts say Prime Minister Abhisit Vejjajiva came to power illegally and are demanding that he stand down, something he has refused to do.
The stand-off is estimated to have cost the Thai economy tens of millions of dollars, with some of the capital's key tourist and entertainment districts virtually paralysed.
The ongoing tensions have meant many Bangkok residents have welcomed the troops in the hope that they will be able to bring the crisis to an end.
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