WASHINGTON, Dec. 23 (Xinhua) -- One day after his nuclear weapons tweet sent jitters across the world, U.S. President-elect Donald Trump on Friday further suggested that he was open to arms race.

"Let it be an arms race... we will outmatch them at every pass and outlast them all," Trump reportedly told MSNBC in an off-air conversation.

Less than one month before taking office, Trump caused alarm on Thursday by writing on Twitter in ambiguous language and just 118 letters that the United States must boost its nuclear capability.

"The United States must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes," Trump wrote.

It remained unclear what caused Trump to weigh in on the issue. However, hours before what appeared to be the New York billionaire developer's impromptu statement on unclear weapons, Russian President Vladimir Putin said in a speech that Russia needed to "strengthen" its nuclear forces.

Speaking in an interview with NBC on Friday, Trump's incoming White House Press Secretary Sean Spicer declined that Trump's tweet on nuclear weapons on Thursday was "a shoot from the hip reaction" to Putin's speech.

"There's been several countries, Russia among them, that have talked about expanding their nuclear capability. The point that he was making was very clear," said Spicer.

In the same interview, Spicer also claimed that there would not be an arms race.

"There's not going to be (arms race) because he's going to ensure that other countries get the message that he's not going to sit back and allow that," he said.