Accusations regularly fly between Washington and Tehran about their involvement in Iraq, but the past few weeks have seen these charges take a more specific turn. The U.S. military in recent weeks has accused Iran of arming Shiite militias inside the war zone. What’s more, an unnamed U.S. official told the New York Times that Hezbollah, the Lebanon-based terrorist group, has been training Iraqi fighters at a base near Tehran. The government of Iran, meanwhile, has pulled out of a fourth round of bilateral talks over Iraqi security to protest what Tehran calls the “massacre” (aj-Jazeera) of innocent civilians in Iraq by U.S.-led forces. The Pentagon says it is only bombing fighters suspected of receiving Iranian backing.

Caught in the middle of the diplomatic fracas is Iraq’s Shiite-led government. After months of mounting U.S. claims of Iranian interference, a delegation of Iraqi lawmakers traveled to Tehran to discuss new evidence (Reuters) said to implicate Iran in cross-border meddling. The alleged links, amassed by the U.S. military but so far classified, are said to include proof Iranian manufactured weapons are being used to kill U.S. and Iraqi soldiers. A military official told CFR.org on background last month recent weapons caches uncovered include rockets with serial numbers traceable to Iran. Charges of Hezbollah-staffed training camps, in particular, have some urging action: John Bolton, the former U.S. ambassador to the UN, says any camp harboring militants should be targeted by “military force” (Telegraph) to show the Iranians “we’re not going to tolerate this.” But mixed messages from the Iraqi delegation highlights Baghdad’s balancing act in juggling relations with competing powers (LAT). Ali al-Dabbagh, an Iraqi government spokesman, was quoted by an Iranian news agency as suggesting claims of Iranian interference were “speculation” (Fars). Dabbagh later told reporters he was misinterpreted, and said Iraq is forming a committee to investigate allegations of interference (Armed Forces Press Service).

For the United States, pointing a finger at Iran is seen by some analysts as an attempt to rally support for Iraqi government forces at a crucial moment. The government this year has challenged militias loyal to firebrand cleric Muqtada al-Sadr and reports from one Baghdad neighborhood suggest popular support for his Madhi army—which the U.S. alleges receives Iranian aid—may be slipping (Longwarjournal.com). Residents of Sadr City, the 2.5 million Baghdad slum that is a base of Sadr support, are fleeing escalating violence there (NPR). The U.S. and Iraqi governments also seek to isolate Sadr, the Shiite Iraqi cleric who is thought to be studying in the Iranian religious city of Qom. The cleric refused to meet (RFE/RL) with the Iraqi delegation during their visit last week.

Some experts speculate Iran wants to ensure a Sunni-led government never returns to power in Iraq. Others suggest Iran favors a kind of managed chaos in Iraq, to keep the U.S. military busy. But lackluster U.S. intelligence on Iran makes some of this a guessing game. As Kenneth Pollack of the Brookings Institution writes in the Nation, “Iran is putting money on every number of the roulette wheel.” Complicating matters are ties between Iran and Iraq’s Shiite politicians, many of whom spent the Hussein era in Iran (PDF).

Despite Iranian vows to halt bilateral security talks, some channels remain open. Senior U.S. officials in Baghdad have received back-door communications from Tehran (WSJ) in the recent past. An International Crisis Group report suggests such negotiations be brought to the front door (PDF). The report concludes that lasting stability will require “engaging in real diplomacy with all Iraq’s neighbors, Iran and Syria included.”