Nato allies backed keeping Patriot missiles in Turkey yesterday, agreeing with Ankara that threats from the civil war in Syria remained serious, an alliance official said.

The Netherlands, Germany and the United States, which deployed the missiles to Turkey, must now take national decisions on keeping them there, the official said.

In Germany and the Netherlands that requires parliamentary approval. All three nations said they were in favour of keeping the missiles in Turkey provided they gained the necessary approvals at home, a Nato source said.

The three countries each sent two Patriot missile batteries and soldiers to operate them at the start of this year after Turkey asked for Nato help in increasing border security.

They were initially expected to remain for up to a year but no time limit was set. Nato ambassadors discussed the situation yesterday and “agreed that the overall risks and threats to Turkey remain serious,” the official said, speaking on condition of anonymity. They did not specify how much longer the missiles should remain.

Turkey has been one of President Bashar al-Assad’s fiercest critics, leading calls for international intervention in the conflict, supporting the Syrian rebels and providing shelter for nearly 700,000 Syrian refugees.

The frontier has become a flashpoint in the civil war, now in its third year, with shells fired from Syrian territory frequently landing inside Turkey, drawing a response in kind from the Turkish military.