Nordic ships turn back as first tranche of stockpile has not yet arrived at port, but Obama administration plays down delay

Syria failed to meet a deadline on Tuesday to hand over the first tranche of its chemical weapons stockpile, with two Nordic ships sent to collect it forced to turn back.

Security concerns, bureaucracy, bad weather and a complex multinational procurement effort for equipment were the reasons for the delay, an official from the UN's Organisation for the Prohibition of Chemical Weapons (OPCW) said.

Under a groundbreaking US-Russian deal, Syria pledged to destroy all of its chemical weapons by June 2014. Damascus agreed to transport the "most critical" chemicals, including around 20 tons of mustard nerve agent, to the northern port of Latakia by 31 December. They have not yet arrived.

On Monday the Norwegian frigate HnoMS Helge Ingstad, which was meant to pick up the dangerous cargo, returned to Cyprus empty-handed. An escorting Danish warship also turned back. It was unclear when the ships might make a second trip to Syria's Mediterranean coast. "We are still on high alert to go into Syria," said the Norwegian ship's spokesman, Lars Hovtun.

The Obama administration has sought to play down the missed deadline, with officials suggesting the plan to remove President Bashar al-Assad's chemical arsenal remains on track. "As long as we see forward progress that's what's most important here, and we have," Marie Harf, the US state department's deputy spokesperson, said on Monday.

The OPCW said: "Preparations continue in readiness for the transport of most of the critical chemical material from the Syrian Arab Republic for outside destruction."

Nonetheless, Syria's non-compliance will raise fears that the Assad regime may intend to delay the process for as long as possible. Further delays would highlight the west's impotence and paralyse the debate over intervention. The missed deadline comes at a time when some western leaders privately concede that Assad's continued survival is Syria's least worst option.