WASHINGTON, July 9 -- US President Donald Trump's nominee for ambassador to Singapore, Dr Anjani Sinha, came under tough questioning during his Senate confirmation hearing, struggling to defend the administration's tariff policies and demonstrate knowledge of US-Singapore relations.

The Straits Times reported that Dr Sinha, a retired orthopaedic surgeon, faced intense scrutiny from Democratic Senator Tammy Duckworth, who expressed doubts about his qualifications and preparedness for the role during a two-hour session before the Senate Foreign Relations Committee.

"This is not a role you can just pick up on a whim, or because you think it will be glamorous," Duckworth was quoted saying, questioning his grasp of key economic and diplomati...