WASHINGTON (AFP) - President Donald Trump's national security team was finally completed on Wednesday (March 15) when former senator Dan Coats gained final approval in Congress as director of national intelligence.

The Senate formally endorsed Coats, a moderate Republican who represented Indiana in the body until the beginning of January, by a vote of 85 to 12.

The White House has struggled to build a team for national security and military policy. Trump's first choice for his essential national security adviser, Mike Flynn, was forced to resign after allegedly misrepresenting the content of December phone calls with the Russian ambassador.

Coats was nominated on Jan 7, but was placed near the bottom of a list of Cabinet-level officials requiring Senate approval.

As director of national intelligence, he will be in charge of coordinating 17 bodies in the national security sphere, including the Central Intelligence Agency, the National Security Agency, the Defence intelligence agency and the Federal Bureau of Investigation.

Coats, 73, served as a Republican senator from Indiana from 1989 to 1999, and then from 2011 to the end of his term on Jan 3.

He was US ambassador to Germany from 2001 to 2005 under the George W. Bush administration.

He was one of six US legislators and three White House aides blacklisted by Moscow in 2014 in reprisal for US sanctions placed on the country for its seizure of the Crimean Peninsula from Ukraine.

A strong advocate for sanctions against Moscow, Coats called the ban an honour.

But in his confirmation hearing at the Senate intelligence committee on Feb 28, his former colleagues warned he might be "too nice" for a job in a White House where some Cabinet officials are already at odds with Trump advisers over policies and staffing.

"You're one of the most likeable, affable easy-going people I've met," said Senator Angus King.

"I'm not sure likability and affability are the qualities I want in this position," he said.

"You're going to be reporting to a president who may or may not want to hear what you have to say."