Iraqi security forces were routed by ISIS fighters earlier this month during a lightning advance that saw the al Qaeda offshoot seize large swaths of northern and western Iraq.
State-run Iraqiya TV reported that the Iraqi army and volunteer militia groups had cleared ISIS fighters from the city, having advanced on the city from four directions.
Sheikh Khamis al-Joubouri, a key tribal leader in Tikrit, told CNN on Saturday that the Iraqi security forces entered the city supported by special forces and fighters from among the local tribes and had gained control.
He said ISIS fighters retreated in the direction of Kirkuk and the province of Nineveh.
But a combatant told a CNN freelance reporter that ISIS fighters remained in control of Tikrit, though there were fierce clashes in an area about 20 kilometers (12 miles) from the city center, toward Samarra.
Two security officials in Samarra told CNN that Iraqi soldiers stopped the militants' advance about 10 kilometers (6 miles) south of Tikrit because ISIS had planted mines and booby-trapped houses.
State-run TV aired footage Sunday of the arrival overnight of five Russian Sukhoi fighter jets. They are the first of 25 warplanes expected to be delivered under a contract agreed to by Moscow and Baghdad, the Ministry of Defense said in a statement provided to CNN.
The announcement follows a comment by al-Maliki that militant advances might have been avoided if Iraq had proper air power, in the form of fighter jets that Iraq has been trying to get from the United States.
"I'll be frank and say that we were deluded when we signed the contract" with the United States, al-Maliki told the BBC in the interview last week, which was released Friday.
Iraq has now turned to Russia and Belarus to buy fighter jets, he said. "God willing, within one week, this force will be effective and will destroy the terrorists' dens," he said.
U.S. officials were quick to reject al-Maliki's complaints. U.S. fighter jets have not been slow in coming, Pentagon spokesman Rear Adm. John Kirby told CNN. The first two promised F-16s "weren't expected to be delivered until the fall, which is still months away," Kirby said. "And we were in the process of working towards that delivery."
The advance of the al Qaeda splinter group "couldn't have been stemmed through the use of two particular fighter planes," he said.
Al-Maliki's statements about the need for air support came as American and Arab diplomats told CNN that the United States is unlikely to undertake any military strikes against the militant group, the Islamic State of Iraq and Syria, and its allied fighters before a new government is formed in Iraq.
State Department: Iraq helped create this problem
U.S. State Department spokeswoman Marie Harf told CNN that Iraq helped create the crisis.
"This kind of blame of others on the outside is quite frankly part of what's gotten Iraq into the situation it's in today. It's helped create the crisis. When we left Iraq, we gave the Iraqis the ability to create a better future," she said. "And unfortunately, leaders across the spectrum didn't step up and take the opportunity. They blamed others and didn't bring the country together."
Al-Maliki and his Shiite-dominated government have been under pressure by the Western and Arab diplomats to be more inclusive of Iraq's Sunni minority, who say they have been marginalized and cut out of the political process by the government.
Al-Joubouri said that the Sunni tribes in and around Tikrit were not aligned with the government or with ISIS and had stayed out of the fight until now.
But, he said, when ISIS fighters who arrived in Tikrit robbed banks and carried out executions, as well as bringing the local economy to a standstill, the tribal leaders offered their help to the Iraqi security forces poised outside the city.
The tribal leaders shared their knowledge of the city, including routes and known ISIS positions, he said.