London: US President Barack Obama on Sunday ruled out any plans to send American ground troops in strife- torn Syria, saying it would be a "mistake" to deploy American or British soldiers to overthrow the Bashar al-Assad regime.
Obama, who has been in the UK for a three-day visit which has included a birthday lunch with Queen Elizabeth II and strong interventions in favour of Britain staying within the European Union (EU), said Syria was a "heart-breaking situation of enormous complexity".
"I don't think there are any simple solutions? It would be a mistake for the US, or Great Britain to send in ground troops and overthrow the (Bashar al-) Assad regime," he told the BBC in an interview.
"In order for us to solve the long-term problems in Syria, a military solution alone - and certainly us deploying ground troops - is not going to bring that about," he said.
Obama said the US-led coalition would continue "to strike ISIS (Islamic State) targets in places like Raqqa, and to try to isolate those portions of the country, and lock down those portions of the country that are sending foreign fighters into Europe".
He had earlier said that Europe would be safer with Britain voting to stay in the EU in the June 23 referendum and be able to tackle terrorism more effectively from within.
Obama warned that Brexit could hit Britain economically and take as long as a decade to negotiate a UK-US trade deal.
"It could be five years from now, 10 years from now before we were able to actually get something done. The UK would not be able to negotiate something with the United States faster than the EU. We wouldn't abandon our efforts to negotiate a trade deal with our largest trading partner, the European market," he told BBC.
However, his warning over UK-US trade deals has angered campaigners in favour of leaving the EU, with some describing him as a "lame duck" President who will be out of office soon.
Meanwhile, the Democratic US presidential hopeful Hillary Clinton also made it clear this week that she thought it would be a mistake for the UK to leave the union.
But London mayor Boris Johnson, one of the leading voices in the Leave camp, believes the UK could be in a more favourable position to strike a trade deal with the US if it left the EU.
The issue has dominated Obama's UK visit as he leaves for Germany to hold talks with Chancellor Angela Merkel, with the main aim being to win public support in Germany for a planned US-EU free trade deal.