Secretary of State John Kerry made a surprise visit to Iraq today, visiting Prime Minister Nouri al-Maliki and pressing him to stop allowing Iranian flights to Syria from crossing over Iraqi territory, insisting they were carrying “arms and fighters” to the Syrian government.

This has been a long-standing complaint of the US, but officials have never presented any actual evidence to the public that this is the case, and today only insisted that the sheer volume of the overflights proved it must be weaponry. Maliki insisted that barring evidence they will not do anything.

Iran maintains that it is only shipping humanitarian aid to Syria, and Iraq has searched planes at random in the past, but insists that everything they found on those planes was exactly what Iran said, humanitarian aid. They have stopped the searches saying that there is no evidence to justify continuing them.

As the US picks up aid to the Syrian rebels, it is inevitable that they would hope to see Iraq clamp off the Assad government’s own sources. Yet with the Syrian rebels linked so closely to the Iraqi insurgency, the Iraqi government’s interests are decidedly different, and lacking evidence of any unlawful arms shipments in their airspace, there is little motivation for Iraq to do anything of the sort.