The presidents of the US and Russia will meet face to face this evening for the first time in two years.

They will sit down after both have addressed the United Nations General Assembly in New York, which gets underway later.

However there has been no straight answer on who called the meeting.

Tensions surrounding the actions of the Syrian President Bashar al-Assad and a strategy to tackle Islamic State (IS) are both expected to be high on the agenda for world leaders at the summit.

Victoria Jones is chief White House correspondent with Talk Radio News Service in the US.

She says the meeting between Barack Obama and Vladimir Putin is significant.

"President Obama basically has cut Putin off since Putin annexed Ukraine, and also Putin hasn't been to the UN General Assembly for the last 10 years" she told Newstalk Breakfast.

"Also the Obama administration is flummoxed over what Putin is doing in Syria right now - and President Obama has decided the best thing is to just ask him directly" she added.

While the British Prime Minister says Syrian President Bashar al-Assad must face a war crimes trial.

David Cameron was speaking in New York - where world leaders are gathering for a meeting of the UN.

Mr Cameron's stance puts him at odds with Syria's most powerful backers - Russian President Putin and Iranian President Hassan Rouhani.

They say Mr Assad's removal would make Syria a haven for terrorists.

While the Foreign Affairs Minister Charlie Flanagan will attend United Nations summits in the US this week.

The UN summits will focus on Peacekeeping Operations and Countering Extremism, and will be convened by President Obama.

Minister Flanagan is on a five-day visit to the United States.