US Deputy Defence Secretary Paul Wolfowitz was speaking after talks in Ankara, but the Turkish foreign minister has said his country made no firm commitment.
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Is this the start of misbehaviour...?
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Iraqi Foreign Ministry
In Iraq itself, United Nations weapons inspectors checked two sites which featured in Saddam Hussein's past chemical weapons and nuclear programmes.
As the visits entered their seventh day, the Iraqi Government made its first criticism of the inspectors, describing their conduct on Tuesday as "misbehaviour".
Mr Wolfowitz said the US and Turkey had found common ground on Iraq.
"We have an agreement to move forward with concrete measures of military planning and preparations," Mr Wolfowitz said after meeting Turkey's top leaders, including members of the Islamist-rooted party which won the recent election.
America, he said, planned to spend "several hundred million dollars of investment in several facilities".
Turkish caution
Contrary to earlier reports, Turkish Foreign Minister Yasar Yakis said on Wednesday that his country had not agreed to allow the US use of its military bases in the event of UN-approved military action.
"Turkey has not made any commitment to the USA," he said, adding that an initial statement he made had been "misinterpreted".
But Turkish Prime Minister Abdullah Gul said the government had not yet made a final political decision on the Iraq issue.
In Washington, Defence Secretary Donald Rumsfeld has insisted that Iraq does have weapons of mass destruction despite its repeated denials.
"Any country on the face of the earth with an active intelligence programme knows that Iraq has weapons of mass destruction," he said.
In Delhi, Russian President Vladimir Putin and Indian Prime Minister Atal Bihari Vajpayee have urged a peaceful solution to the Iraq crisis and warned against taking unilateral military action.
Iraq has until Sunday to supply an account of all of its weapons programmes to the UN.
Poison gas factory
Inspectors spent about four hours visiting a former chemical weapons plant at Muthanna, 70 kilometres (40 miles) north-west of Baghdad.
By Iraq's own admission, Muthanna produced 4,000 ton of chemical warfare agents including mustard gas and sarin a year until it was demolished by previous UN inspectors in the 1990s.
Also on Wednesday, a team sent to the former nuclear facility at Tuwaitha - just south of the capital - spent five hours there before leaving.
Tuwaitha is the site of the Osiraq nuclear reactor bombed by Israel in 1981 and several ton of uranium have been under seal there since 1998.
Unmovic staff arriving at Muthanna were rapidly admitted by guards into the vast desert installation despite the surprise nature of the inspection.
'Spying'
Iraq's Foreign Ministry has said that the inspectors' visit to the Sijood palace on Tuesday raised questions about their objectivity.
"Is this the start of misbehaviour which would recreate the climate which marked relations between previous arms inspection teams and Iraq?" it asked in a statement, carried by state media.
The ministry also warned inspectors against "spying on targets that are not mentioned in UN Security Council resolutions".
General Hussam Mohammed Amin, the chief Iraqi liaison officer, insisted on Tuesday that Iraq was "devoid of weapons of mass destruction".
The Iraqi Government also dismissed the Iraq human rights dossier published by the British Government on Monday as "lies".
Iraq faces US-led military action in the event of a serious breach of its commitment to allow arms inspections.