Russia announced Monday that it has agreed to push on with a deal to deliver S-300 missile systems to Iran after Moscow halted an earlier agreement due to UN sanctions slapped on Tehran.

"The contract between Russia and Iran for delivery of S-300 missile systems is back in force," the state-run Russian Technologies corporation said in a statement, adding that the two sides had "signed a contract".

Moscow in April lifted a ban on selling the missile systems to Iran, ahead ofTehran sealing a final historic deal with world powers in July to curb its nuclear programme.

The decision sparked condemnation from Israel and concern from Washington, as it came before the lifting of the sanctions by theUN Security Council. =

Moscow blocked deliveries of the surface-to-air missiles to Tehran in 2010 after the UN Security Council imposed the curbs on Iran over its nuclear programme barring hi-tech weapons sales.

Moscow says its has now offered Tehran more modern versions of the weapons but has yet to announce publicly when they will be delivered.

Russia and Iran are allied over their back-

ing for Syrian President Bashar al-Assad, with both sides helping regime forces fighting on the ground.

Meanwhile, the US air force secretary yesterday said the air campaign against the Islamic State group has made progress in degrading the jihadist organisation but will not be enough without local boots on the ground.

The comments from Deborah Lee

James come just days after Pentagon chief Ashton Carter raised the possibility of deploying additional US special forces personnel to Syria.

"Air power is extremely important. It can do a lot but it can't do everything," James said. "Ultimately it cannot occupy territory and very importantly it cannot govern territory," she told reporters at the Dubai Airshow.