The first additional American troops who will take part in a major new security plan in Baghdad have arrived in the Iraqi capital, the US commander in Iraq, General George Casey, said Monday.

"The initial elements of the first group are here," he told a news conference. He declined to give more details or say when operations would start but he said a report that 4,000 of the planned 17,500 extra troops had arrived was "real high".

Asked about reports of frustration among US officials with Iraqi counterparts over the planning of an operation to be led by the Iraqi government with US help, Casey said: "Transitions generate friction. And we are in a period of transition."

But he said US and Iraqi officials were working hard to ensure a workable command structure that would allow Iraqi control while maintaining the security and effectiveness of US troops.

"We are working out understandings at every level to ensure there are no misunderstandings," Casey said.

"This is a plan that is Iraqi-conceived but we have been involved every step of the way," he said. "American forces will remain under American command... Our forces will not be put at risk because of the command relationship."

He said he was confident the Iraqi government would "purge" elements from its security forces which were loyal to militias and other groups outside the government.

Casey cautioned the Iraqi public not to expect an instant improvement in security in the capital. "It's not going to happen overnight," he said, speaking of a "gradual evolution" over two to three months, with the hope of showing results in the summer or autumn.

Asked how long it would last, he said: "Until we succeed... until the job is done."

Senior Iraqi officials said it would last at least six or seven months.

US plans to crack networks

The United States plans to "go after" what it said were networks of Iranian and Syrian agents in Iraq, US Ambassador Zalmay Khalilzad said Monday.

"We're going after their networks in Iraq," he told a news conference, as he laid out the new US and Iraqi strategy to end sectarian violence by both Sunnis and Shi'ites at what Khalilzad called a "defining moment" for Iraq.

US forces are holding five Iranians following a raid on an Iranian government office in Arbil last week the second such operation in recent weeks.

Khalilzad and Casey denied there was any disagreement between Washington and Iraqi Shi'ite Prime Minister Nuri al-Maliki over the detentions.

Iraq's foreign minister has endorsed Iranian calls for the release of the five men.

"We will target these networks in the... expectation of changing the behavior of these states," Khalilzad said.

He said some of the five arrested in Arbil were members of the Quds Force of Iran's Revolutionary Guards, which he said was directly involved in supplying weapons to militants in Iraq.

(China Daily via agencies January 16, 2007)