US President Donald Trump says he wants to expand America’s nuclear arsenal to ensure it is at the "top of the pack," saying the US has fallen behind in its nuclear weapons capacity.

A political analyst believes Trump’s plan to expand US nuclear arsenal is a “grave threat” to global security, adding that the last thing the world needs at this point is more nuclear weapons.

“Unfortunately Donald Trump does not seem to understand his obligations under past treaties nor does he understand the realities of the world which is threatened by this ultimate weapon,” Einar Tangen told Press TV in an interview on Friday.

He also noted that Trump has made a “radical departure” from the past, arguing that “he has literally turned the United States 180 degrees” not only on the issue of nuclear weapons but also in terms of trade.

The analyst went on to say that Trump’s insistence that he needs to be "number one is reminiscent of his time in reality TV and in business."

However, he said, Trump needs to understand that he cannot impose his will upon others for being "number one" in the world, asserting that he cannot afford to be a "playground bully the way he was in his past life."

Tangen also expressed hope that there would be people in Trump’s administration to explain the "cost and consequences of what he is proposing."

The analyst further stated that Trump has no respect for “continuity” and for that reason he thinks that only he can "negotiate a good treaty or deal."

“It is this kind of very odd idea that his ego is somehow a replacement for common sense,” he added.