Four Russian cruise missiles fired at Syria from the Caspian Sea landed in Iran, unnamed US officials say.

It was unclear whether the missiles caused any damage, they said.

On Wednesday, Russia said it had launched 26 cruise missiles at targets in north and north-west Syria. It has reiterated comments made at the time that all reached their targets.

The news came as NATO renewed assurances to defend its allies in view of Russia's "escalation" in Syria.

NATO is boosting its response forces to be able to deploy troops speedily.

The US officials provided no details of where the missiles might have landed.

However, Iran's Irna news agency reported on Wednesday that an unknown flying object had crashed in the village of Ghozghapan in the Iranian province of West Azerbaijan, said to be under the missiles' flight path.

Moscow denies Western accusations that it has mainly targeted opponents of Syrian President Bashar al-Assad, insisting its strikes have hit the infrastructure of the so-called Islamic State (IS) and other militant groups.

IS militants have seized swathes of territory in Syria and Iraq.

The Russian air strikes had "weakened" IS, Syrian Army Chief of Staff Gen Ali Abdullah Ayoub said on Thursday, enabling the army to start a "big attack" to retake towns and villages.

Heavy fighting was reported in areas of Idlib, Hama and Latakia provinces, where a coalition of rebels - including the al-Qaeda-linked Nusra Front - operates.

Government-backed troops had moved into the key Ghab plain area, the UK-based Syrian Observatory for Human Rights monitoring group said. (Source: BBC News)

Story Date: October 9, 2015