Disarmament teams returned Scandinavian escort vessels to port Monday as they accepted an end-of-year deadline for the removal of Syrian chemical weapons could no longer be met, a Norwegian spokesman said.
Norwegian frigate HNoMS Helge Ingstad was ordered back to port in the nearby island of Cyprus along with a Danish warship that had been deployed to escort the dangerous cargo to destruction under international supervision, spokesman Lars Hovtun said.
He gave no new date for the planned shipment.
"We are still on high alert to go into Syria," Hovtun said. "We still don't know exactly when the orders will come."
The international disarmament mission in Syria had acknowledged on Saturday that it was "unlikely" the weapons could be transported to the Syrian port of Latakia in time for the December 31 deadline set for the removal of key weapons components.
The year-end deadline was the first key milestone under a UN Security Council-backed deal arranged by Russia and the United States that aims to wipe out all of Syria's chemical arms by the middle of 2014.
"Preparations continue in readiness for the transport of most of the critical chemical material from the Syrian Arab Republic for outside destruction. However, at this stage, transportation of the most critical chemical material before 31 December is unlikely," said a joint statement from the UN and Organisation for the Prohibition of Chemical Weapons.
Signup to our newsletter and follow us on Facebook and Twitter!
Syria's worsening civil war, logistical problems and bad weather had held up the operation to move chemical agents to the port of Latakia, the two bodies said.
Under an internationally agreed plan, the chemicals will be taken to a port in Italy where they are to be transported to a US Navy ship specially fitted with equipment to destroy the weapons at sea.
Washington said Monday that it was "the Assad regime's responsibility to transport the chemicals to the port safely, to facilitate their removal."
"We expect them to meet that obligation," stressed State Department deputy spokeswoman Marie Harf.
But she also recognised that it was "a complicated process... as long as we see forward progress that what's most important here."
The US-Russia deal for Syria to surrender more than 1,000 tonnes of chemical agents averted US-led military strikes after a chemical weapons attack on August 21 near Damascus that the United States says killed 1,400 people.
Harf highlighted how much had been achieved since the chemical arms deal was struck in September including "the functional disablement of all Syria's declared production, mixing and filling equipment".
"Which basically means they can't take the chemicals they have and weaponise them."
And she stressed the international effort was still operating under an "ambitious timeline" which should see the stockpile completely destroyed by June 30.