Tension is rising on Turkey's border with Iraq amid speculation Ankara may be about to launch an incursion to tackle Kurdish rebels.
Turkey blames the rebel PKK for recent attacks
Turkey is continuing a military build up and Prime Minister Recep Tayyip Erdogan has refused to rule out action.
Turkey blames rebels of the PKK group for a recent suicide bombing in Ankara and a landmine attack on troops.
The PKK has been fighting for an ethnic homeland since 1984. Turkey blames the group for 30,000 deaths since then.
Reports from south-east Turkey say the military build-up includes about 20 tanks being sent to the Iraq border.
Turkey has an ongoing military campaign against the PKK, or Kurdistan Workers' Party, inside its borders but the US has warned Ankara that sending troops into Iraq would only complicate the situation.
Last week two US F-16 fighter jets based in Iraq made an incursion into Turkish airspace that Turkish media said was an attempt to intimidate Ankara into refraining from any action inside Iraq.
The US said the violation of the airspace was "unintended" and was under investigation.
Mr Erdogan warned Washington there should be no repeat.
In an interview with the private NTV news channel he said Iraq the US and Turkey should carry out a joint operation against the PKK.
"When the United States says that they do not consider a unilateral operation right, this could mean that we can carry out an operation altogether," he said.
However, when asked if he had given an assurance to the US that Turkey would not carry out its own operation, he said: "We cannot make any concessions to this end."
Thousands of PKK members are thought to operate in mountainous regions of Kurdish-dominated northern Iraq.
Pressure for renewed action mounted last week after a landmine attack killed six Turkish troops close to the Iraq border.
Two days earlier a suicide bombing killed six people in Ankara. Authorities blamed the PKK but the group denied any involvement.
Analysts say with national elections scheduled for July, Mr Erdogan may feel the need to act strongly.