Washington D.C.: US President Donald Trump on Saturday alleged that House Speaker and Democratic leader Nancy Pelosi is being controlled by the "radical left", as he reiterated his demand for building a wall along the US-Mexico border to prevent the flow of illegal aliens and massive smuggling of drugs.

"Well, I hope that Speaker Pelosi can come along and realise what everybody knows, that no matter who it is, they know that walls work. We need walls. Whether it's personal or not, it's not personal for me," Trump said at the White House before leaving for Dover Airforce Base for the return of remains of four Americans killed in Syria this week. He will also visit the families.