"I think it is pretty difficult to say troops shouldn't [invade] when the Turkish soldiers are being killed, and their villages attacked"
Celtic, Karlstad, Sweden
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Morrell also said: "We are making efforts to help them get actionable intelligence.
"Actionable" intelligence refers to information that can be acted upon, such as information that pinpoints the location of a target for a military strike.
Turkey has threatened to send its forces across the border into northern Iraq against the Kurdish Workers' party (PKK) in response to stepped up attacks inside Turkey by the separatist group.
Morrell said the US has shared intelligence - a "lot of intelligence" - with Turkey for a long time, but has increased intelligence sharing recently.
Turkey, which has Nato's second biggest army, has deployed as many as 100,000 troops on its border with Iraq, and says it will launch a major cross-border incursion against the PKK unless US and Iraqi forces act.
For its part, Iraq announced on Wednesday that it was setting up further checkpoints to restrict the passage of Kurdish fighters and to cut supply lines.
Last week, Robert Gates, the US defence secretary, said Turkey and the US needed better intelligence about the location of PKK fighters in Iraq before launching a military strike. Gates would not discuss intelligence last week.
Morrell would not say how the US was gathering the intelligence.
A Turkish army statement said that the latest fighting was in the Cudi mountains in Sirnak province where Cobra helicopters and artillery had been pounding PKK positions since Monday.
Three soldiers were killed in the clashes, the army said.