(ANSA-AFP) - LONDON, SEP 20 - Britain's new Prime Minister Liz Truss on Tuesday vowed billions more in financial and military aid to Ukraine as she kicked off her debut foreign trip at the UN General Assembly. Ahead of her first meeting with US President Joe Biden, Truss also conceded that a post-Brexit UK-US trade deal was unlikely for years. "There aren't currently any negotiations taking place with the US and I don't have an expectation that those are going to start in the short to medium term," she told reporters en route to New York. At the UN, Truss is also due to meet French President Emmanuel Macron and EU commission chief Ursula von der Leyen. Like Biden's White House, they are unhappy with her hard line on Brexit and Northern Ireland. But Truss vowed to rally Western support at the UN over Ukraine, saying her government would match or exceed the £2.3 billion ($2.6 billion) it plans to extend this year. (ANSA-AFP).