US pours cold water on German plan for Syria

"We're looking for a solution that includes the international community," she said.

"It will be a long process, a difficult road," she added.

She spoke after Turkish president Recep Tayyip Erdogan, a Nato member, and Russian president Vladimir Putin, Nato's main adversary, met in Sochi, Russia, on Tuesday to agree details of northern Syria troop deployments.

The new crisis arose after US president Donald Trump pulled out his soldiers two weeks ago, paving the way for Turkey, Russia, and Russia's ally, the Syrian regime, to pour in their armies instead.

Kramp-Karrenbauer's idea represented a bold shift in German foreign policy, which used to abhor overseas military action.

But the US said it would not take part.

"The proposal is that European partners want to carry out joint patrols in this new corridor. I think that's good," US defence secretary Mark Esper told press after the Nato meeting.

"[But] we do not intend to contribute ground forces or anything else to this operation," he said.

"There has been no specific call for any Nato troops in northeast Syria or in Syria," Nato secretary general Jens Stoltenberg added.

German troops are also unlikely to take part because the centre-left SPD party in the ruling coalition would not allow it.

"That means a militarisation of German foreign policy, and the SPD cannot and will not participate in such a thing," the party's deputy chief, Ralf Stegner, said in Berlin on Thursday.

Nato military experts and ambassadors will hold talks on Germany's proposal in the run-up to a Nato summit in London in December.

The Turkish defence minister, Hulusi Akar, also said he was "very open" to it and German foreign minister Heiko Maas is to visit Ankara on Saturday.

But even if Nato states agreed to go ahead, Russia has little incentive to give back the strategic position it has taken up on Turkey and Nato's southern border.

There would need to be "a process in the UN" to create a legal mandate for any international mission, Stoltenberg noted on Thursday.

And Russia has already vetoed international action on Syria 14 times in the UN Security Council.

Trump's Syria pull-out and Turkey's invasion had caused another rift among Nato allies.

Kramp-Karrenbauer herself compared Erdogan's actions to Putin's invasion of Ukraine when she visited German soldiers at a base in Erfurt, Germany, earlier this week.

Turkey had "illegally annexed territory, expelling people there," she said, referring to Kurdish forces in the region, whom Erdogan calls "terrorists".

But Stoltenberg and Esper played down the West's intestinal turbulence.

"There are different views, but we agree on several things, including that Turkey has legitimate security concerns," the Nato head told press in Brussels.

"The United States commitment to Nato and to Article 5 is ironclad," the US military chief said, referring to the Nato treaty's mutual defence clause.

Northern Syria also hosts thousands of prisoners from Isis, a militant Islamist group responsible for bombings and shootings in Europe.

And Stoltenberg warned there was a "risk of jeopardising the progress we've made in the fight against Da'esh [another name for Isis]", if the jihadists broke loose.

Russia and China

But for his part, Esper, in a speech at the German Marshall Fund, a think tank in Brussels, also issued broader warnings on Russia and China.

"Through predatory economics, political subversion, and military force, they [Moscow and Beijing] seek to erode the sovereignty of weaker states," he said on Thursday.

"China and Russia ... are using their growing power to coercively alter the strategic environment," he added.

He warned poorer EU states against taking part in China's 'One Belt, One Road' plan, a global investment programme, saying China wanted them to "trade sovereignty for financial relief".

But Stoltenberg spoke of a more direct Russian threat after Moscow violated an international arms control pact, the Intermediate-Range Nuclear Forces Treaty.

"More Russian missiles, nuclear-capable missiles in Europe, [are] able to reach European cities within minutes," Stoltenberg said.