Iraq shouldn't allow Iran to use its airspace to provide aid to the Syrian government, US Secretary of State, John Kerry, warned during his unannounced visit to Baghdad.

"I made it very clear that for those of us, who are engaged in an effort to see President Assad step down... anything that supports President Assad is problematic," Kerry said after holding private talks with Iraqi Prime Minister, Nouri al-Maliki.

The Secretary of State added that the silent approval of the Iranian overflights by the Iraqi authorities has left the American people "wondering how it is a partner".

Washington believes that, despite claims that it’s only humanitarian aid, Iran is sending arms and fighters to help Assad in his war against the US-backed National Coalition for Syrian Revolutionary and Opposition Forces.

AP is citing an unnamed US official, who said that such flights occur "close to daily", undermining American efforts to support the rebels.

The flights have long been an issue in the relationship between Washington and Baghdad. In 2012, previous Secretary of State, Hillary Clinton, received a promise from Iraq to check the Iranian flights last year, but since then only two aircraft have been inspected.

Kerry’s comments came after a group of senators sent a letter to President Barack Obama last week, urging him to step up US military efforts in Syria, including destroying Assad's aircraft using precision airstrikes.

Editor of Politics First magazine, Marcus Papadopolous, told RT that it’s “very difficult to tell” whether Iran is providing military support to Assad or not.

But he finds Kerry’s criticism of Iraq’s negligence towards overflights “hypocritical” as there are some other US partners, who made a lot greater contribution to fueling the Syrian conflict.

“It’s ironic given that Turkey, Saudi Arabia and Qatar, who are America’s strategic allies, have been the ones responsible for the bloodshed in Syria through their support for Syrian militants in the form of weapons, cash and Islamist fighters.. And they are the ones, who have blood on their hands and they should be in the International Criminal Court,” Papadopolous stressed.

The civil war has been raging in Syria for over two years, with 70,000 already killed according to UN figures, as Assad and the opposition refuse to sit together at the negotiation table.

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