Turkey’s president has said he would not stop his offensive on northern Syria until “all our objectives had been achieved", defying US sanctions, a European arms embargo and increasing international isolation.
Turkey is in the seventh day of its assault against the Syrian Kurdish forces, which has so far forced more than 150,000 people to flee and left some 60 civilians dead.
"God willing, we will quickly secure the region stretching from Manbij to our border with Iraq and ensure that, in the first stage, one million, and then two million Syrian refugees return to their homes of their own free will," Mr Erdogan said in a televised speech.
Turkey plans to establish a buffer zone stretching hundreds of miles across the Turkey-Syria border to free the area of Kurdish People’s Protection Units (YPG) it considers terrorists.
Mr Erdogan has said he wants to repatriate many of the 3.6 million refugees that it is hosting from the Syrian conflict, however critics have said it could amount to ethnic repopulation.
Overnight on Monday, the US announced sanctions against Turkey’s defence and energy ministries, as well as the ministers of defence, energy, and the interior. Mr Trump also said he was raising sanctions on steel and cancelling a $100 billion trade agreement with Turkey.
Mr Erdoğan appeared unmoved by the prospect, responding by saying: “We have seen all the threat from sanctions to embargoes just because we fight against terrorism,” he said.
But privately Turkish officials are deeply concerned that widespread American sanctions could devastate Turkey’s already flagging currency and sharply drive down the Turkish lira.
A growing number of EU states have piled on pressure, halting arms exports to Ankara over the humanitarian disaster unfolding.
The United Nations, meanwhile, is urging Turkey to investigate reported cases of "summary executions" that could have been committed by a Turkish-backed militia on Kurdish civilians.
Mr Trump on Monday launched a diplomatic effort to broker a ceasefire between Turkey and Kurdish forces after more than a week of US inaction.
Mr Trump spoke by phone to both Mr Erdoğan and the head of the Syrian Democratic Forces (SDF) and called for a halt to the Turkish offensive in Syria.
“President Trump communicated to [Mr Erdoğan] very clearly that the US wants Turkey to stop the invasion, implement an immediate ceasefire, and begin to negotiate with Kurdish forces in Syria,” Mike Pence, US vice president, said.
Mr Pence said he would travel to Turkey at the head of a US delegation to try to broker an agreement. Earlier on Monday, the US imposed sanctions on Turkey’s defence and interior ministers in an effort to put pressure on Ankara.
Mr Trump’s lurch into action came eight days after he appeared to greenlight Turkey’s invasion of northern Syria by telling Mr Erdoğan that US forces would move aside and allow Turkish troops into the region.
But in the face of stinging criticism for the move from fellow Republicans and US allies, Mr Trump appears now to be trying to reverse course and pressure Turkey into calling off the offensive.
Even if Mr Trump is able to broker a deal much of the damage is likely irreversible. The SDF feel deeply betrayed by US actions and have already struck an agreement with Russia and the Assad regime to allow Assad’s forces back into northeast Syria for the first time since 2012.
More than a hundred civilians have been killed in Syria and southern Turkey during the fighting and aid groups say around 200,000 people have been displaced from their homes in the face of Turkish airstrikes and ground assaults.
While Mr Pence addressed reporters and the White House released a statement in Mr Trump’s name calling for a ceasefire, there was silence on Mr Trump’s normally voluble Twitter feed, where he often expresses his unvarnished views.
In a tweet earlier on Monday, he expressed indifference over whether the fighting continued or not.
“Let Syria and Assad protect the Kurds and fight Turkey for their own land,” he said. “Anyone who wants to assist Syria in protecting the Kurds is good with me, whether it is Russia, China, or Napoleon Bonaparte. I hope they all do great, we are 7,000 miles away!”
Fighting continued around the border city of Manbij, where Kurdish and Assad regime forces are trying to hold off an assault by Turkish-backed Syrian rebels. So far, there have been no direct clashes between the Turkish and Syrian militaries.
The US appeared to have effectively handed over one its bases in Manbij to Russian special forces as American troops withdrew from the city.
US officers coordinated a Russian takeover of the facility, according to Newsweek, and Russian media soon began broadcasting from inside the abandoned US facility.
Mr Pence said the US had secured a commitment from Turkey not to attack Kobani, another border city that is of enormous symbolic importance to the Kurds and was until recently a base for US forces.
Mr Trump has ordered all American troops out of Syria with the exception of a small garrison at al-Tanf, a southern base focused on deterring Iran in the country. The move will force the withdrawal of all UK and French special forces in the country.
Mr Pence said he would lead a delegation to Turkey that would include Robert O’Brien, Mr Trump’s new national security advisor.
The vice president’s schedule showed he was due to attend a reception for an ice hockey team at the White House on Tuesday afternoon, so it is unlikely he will reach Turkey until at least Wednesday.