Almotamar.net Google news - The United States accused five Iranians it arrested in Iraq of running arms and money to Iraqi militants as Iraq joined Iran in calling for the men's release.
Washington also told Arab allies it would do more to contain Tehran.
With US forces preparing a big push to avert civil war in Baghdad, Vice President Dick Cheney urged Americans to have the "stomach" to see through a campaign with global ramifications and Iraq's president sought help from another US foe, Syria.
Three days after it stormed an Iranian government office in the Iraqi Kurdish capital Arbil, the US military said five men it seized had ties to the Iranian Revolutionary Guard-Qods Force - "known for providing funds, weapons, improvised explosive device technology and training to extremist groups attempting to destabilise the government of Iraq and attack Coalition forces".
In Tehran, Foreign Ministry spokesman Mohammad Ali Hosseini demanded their immediate release, saying the five were diplomats involved in "consulate affairs". Iraq has said the mission did not yet have consular status but had operated with its approval.
Foreign Minister Hoshiyar Zebari told Reuters the row showed the "thin line" US-occupied Iraq must tread at the heart of the oil-rich Middle East - flanked by Iran, with its links to fellow Shi'ite Muslims dominating the new Iraqi government, and by Sunni-ruled Arab states suspicious of non-Arab Tehran.
"We fully respect the views, policies and strategy of the United States which is the strongest ally to Iraq but the Iraqi government has national interests of its own," Zebari said.
"We can't change the geographical reality that Iran is our neighbour. This is a delicate balance and we are treading a very thin line," he said, adding he hoped the men would be freed.
Iraq's national security minister discussed the issue in Tehran with Iran's intelligence minister, ISNA news agency said.
The Arbil incident was the second such detention in a month and Cheney and US National Security Adviser Stephen Hadley were blunt in comments on Iran in US television interviews:
"You have seen in the last couple weeks that Iranians found doing things in Iraq have been picked up by Coalition forces. And I think you're going to see more of that," Hadley said.
"We intend to deal with it by interdicting and disrupting activities in Iraq, sponsored by Iran, that are putting our troops and Iraqis at risk," he added, while declining to say whether US forces would pursue targets inside Iran.
"Stomach" for fight
Cheney cited concerns about growing Iranian strength among not just Israelis but also Sunni-ruled U.S. Arab allies in the Gulf, Saudi Arabia and Jordan: "The entire region is worried.
"The presence of US military out there ... is indicated as reassurance to our friends in the region that the United States is committed to their security," he said.
President George Bush has been cool to suggestions he seek help from Iran and Syria over Iraq. Talking to Al-Arabiya television, Iranian President Mahmoud Ahmadinejad said he had "no objection" to such dialogue and said he had had a "positive response" from Saudi King Abdullah about helping Iraqis.
But he added: "If they (the Americans) envisage that they can - through dialogue with us or Syria or Saudi Arabia or any other side - undermine the interests of the Iraqi people or ignore them, then they are wrong."
Cheney also defended Bush's decision last week to send more than 20,000 extra US troops to try to end sectarian bloodshed in Baghdad between Sunnis and Shi'ites, describing it as essential to a broader, global front against militant Islam.
He said it was not "just a US show" and that Iraqi Prime Minister Nuri al-Maliki was aware of U.S. expectations he tackle both Sunni rebels and militias loyal to his fellow Shi'ites.
Asked about opposition to the troop deployment in Congress and whether the United States would do "whatever it takes to win", Cheney replied: "I believe we will. If the United States doesn't have the stomach to finish the job in Iraq, we put at risk what we've done in all of those other locations out there."
Secretary of State Condoleezza Rice is on a week-long tour of the Middle East, partly to seek support for the Iraq policy.
Iraqi President Jalal Talabani arrived in Syria, which the United States and Iraqi leaders say lets arms and fighters cross into Iraq in support of Sunni insurgents. Talabani says he wants it to stop and Damascus says it wants to help peace in Iraq.
Little was said after talks between Syrian President Bashar al-Assad and Talabani, who plans to spend some days in a city where he was once exiled. It is the highest level visit since diplomatic relations were restored last year after a quarter of a century of estrangement during the rule of Saddam Hussein.
"We hope the Syrians will help Iraqis stabilise security," Talabani said before leaving. Aides said he will ask Damascus to control its borders. Syria denies helping fighters reach Iraq.