BAGHDAD (AP) ― Iraqi authorities forced an Iranian plane to land on Monday so it could be searched for weapons bound for Syrian regime fighters, but they found only humanitarian aid and medical supplies, officials said.

Also Monday, a series of five bombs targeted security forces across Iraq, killing five and wounding more than a dozen other people, officials said.

The move to force the Damascus-bound plane to land came 10 days after Iraq said it would conduct more searches of aircraft and road vehicles bound for neighboring Syria where rebels are fighting to overthrow Syrian President Bashar Assad.

In a recent visit to Baghdad, U.S. Secretary of State John Kerry confronted Iraqi officials about Syria-bound Iranian flights over its airspace, which the U.S. suspects is being used to ferry weapons and fighters for the embattled Syrian government.

The Iranian cargo plane was found to be carrying “medical and humanitarian aid” and not weapons, government spokesman Ali al-Moussawi said.

“We ordered a surprise landing of a transport plane, but we found no banned items like weapons,” he said.

Iraq has said that it does not want to be a conduit for arming either Assad’s forces or the rebels in the two-year civil war. But Baghdad fears a rebel victory in neighboring Syria will create a new extremist haven on the two nations’ porous 600-kilometer border, sparking further sectarian conflict in Iraq.

Intelligence officials have said al-Qaida fighters in Iraq already appear strengthened by cross-border cooperation with their ideological brothers in Syrian, known as the Nusra Front.

The five attacks across Iraq, which killed two soldiers, two policemen and a pro-government Sunni fighter, came as security forces are on high alert in the lead up to Tuesday’s 10th anniversary of the fall of Baghdad.

There was no claim of responsibility for any of the attacks, but they bore the hallmark of al-Qaida fighters in Iraq, who use car bombs, suicide bombers and coordinated attacks to target security forces.

Police said a roadside bomb targeted an army vehicle in the Baghdad neighborhood of Abu Ghraib, killing two soldiers and wounding another eight.

Three other roadside bombings were reported. One killed a policeman and wounded two in Youssifiyah, 20 kilometers, south of Baghdad. A second wounded three policemen and four civilians in Madain, 20 kilometers southeast of Baghdad. The third killed a policeman in Mosul, 360 kilometers northwest of Baghdad.

In the distant northern city of Kirkuk, about 290 kilometers from Baghdad, a bomb stuck to the underside of a vehicle killed a fighter with the pro-government group known as the Sahwa, which has fought against al-Qaida.

Heath officials confirmed the death tolls.

All officials spoke anonymously because they weren’t authorized to speak to media.