WASHINGTON - President-elect Donald Trump took to Twitter again on Monday evening to promise North Korea would not develop a nuclear missile capable of reaching US territory.

His comments come a day after the North Korean leader, Kim Jong-Un, appeared to try to put pressure on Trump by announcing his country is in the "final stages" of developing an intercontinental ballistic missile (ICBM).

"North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the US," Trump tweeted. "It won't happen!"

Although Washington has repeatedly vowed that it would never accept North Korea as a nuclear state, Trump has not previously clearly stated his policy on the isolated Stalinist state.

The Republican billionaire has already upended precedent by routinely taking to Twitter since his election last month to lambast critics and issue statements - sometimes about the most serious national security issues - sending analysts scrambling to divine what they may mean for US policy once he takes office on January 20.

He launched a solo bid to restart the Cold War arms race last month, tweeting that the United States must "greatly strengthen and expand" its nuclear capabilities.

He has also angered China by tweeting accusations of military expansionism and currency manipulation.

But he will need Beijing, Pyongyang's closest ally, to deal with North Korea's mounting confrontation.

However, he appeared to complicate that prospect with his latest criticism on Monday evening following his vow about North Korea.

"China has been taking out massive amounts of money & wealth from the US in totally one-sided trade, but won't help with North Korea," he tweeted. "Nice!"

US President-elect Donald Trump warned Tuesday against releasing any more terror suspects from the Guantanamo Bay prison, in a bid to preempt any moves before Barack Obama leaves office.

"There should be no further releases from Gitmo. These are extremely dangerous people and should not be allowed back onto the battlefield," tweeted Trump. There are 59 prisoners remaining at the controversial detention center, only a handful of whom have been tried for alleged crimes.

Many are in legal limbo.

Obama came to office vowing to shutter the facility, saying detention without trial did not reflect American values.

But he has run up against political and legal hurdles, Pentagon foot dragging and stubborn Republican opposition in Congress.

With Guantanamo's closure blocked, Obama's White House has focused on whittling down the number of inmates.

George W. Bush had released or transferred around 500 inmates before leaving office, Obama has released or transferred around 179.

Obama's administration is reportedly eyeing further transfers before Trump is sworn in on January 20 - the president-elect having on the contrary vowed to "load (Guantanamo) up with some bad dudes" once in office.

Around 20 of the remaining inmates have been cleared for release. But finding countries to take them has often proven time consuming.

Trump's declaration is the latest in a series of public disputes between Obama and the outspoken president-elect, who has jettisoned the notion there is "one president at a time."