Story highlights WH press secretary denies Trump stumped by reference to START

START is a nuclear weapons treaty between Russia and the US

(CNN) White House Press Secretary Sean Spicer denied President Donald Trump didn't know what a key nuclear disarmament agreement with Russia's president was when the two men spoke by phone two weeks ago.

Spicer insisted Thursday that Trump knew what the US-Russia New START agreement was during his call with Russian President Vladimir Putin and was merely seeking an opinion from an aide when he paused during the conversation.

Spicer was asked the question in reference to a Reuters report which, citing unnamed sources, suggested that Trump had to ask an aide what the treaty was while on the call.

"It wasn't like he didn't know what was being said. He wanted an opinion on something," Spicer told reporters.

Kremlin spokesman Dmitry Peskov said on Friday that he could not confirm reports that the phone call between the two leaders included discussions of the agreement.