A retired admiral, Kirby's new role will see him "coordinate interagency efforts to explain United States policy and (serve) as a senior administration voice on related matters," a White House statement said.

"John understands the complexities of US foreign and defense policy, and he will ably represent the Administration on important national security issues," President Joe Biden said in the statement.

Kirby is a veteran public affairs official, having served in various roles at the Pentagon and US State department, notably as the latter's spokesperson during the Obama administration.

He worked as a military and diplomatic affairs analyst on CNN during the presidency of Donald Trump.

Kirby has gained prominence within the Biden administration since Russia's invasion of Ukraine in February, mainly due to his daily press briefings, which were broadcast live.

"There is simply no other communicator like him, anywhere," his now former boss, US Defense Secretary Lloyd Austin, said in a statement.

The National Security Council advises the American president on foreign policy.