(Adds quotes) BAGHDAD, Jan 15 (Reuters) - The United States plans to "go after" what it said were networks of Iranian and Syrian agents in Iraq, U.S. ambassador Zalmay Khalilzad said on Monday. "We're going after their networks in Iraq," he told a news conference, as he laid out the new U.S. and Iraqi strategy to end sectarian violence -- by both Sunnis and Shi'ites -- at what Khalilzad called a "defining moment" for Iraq. U.S. 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 the U.S. commander in Iraq, General George 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. Khalilzad noted that some Iraqi political organisations that opposed Saddam Hussein from exile had historical ties to security forces in neighbouring countries -- an apparent reference in part to ties between some of Maliki's fellow Shi'ites and the Shi'ite Iranian Revolutionary Guards. "We will target these networks in the ... expectation of changing the behaviour 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. U.S. National Security Adviser Stephen Hadley said on Sunday that there would probably be more such operations against suspected foreign agents.
