South Korean President Park Geun-Hye has addressed a joint session of the US Congress, vowing to maintain strong ties with the US while declaring that she would not accept a nuclear-armed North Korea.
In a speech before legislators on Wednesday, a rare honor given to a foreign head of state, Park also said the South wants to build trust with its northern neighbour.
"It is time to put an end to this vicious cycle," Park said of the continued threats from the North. She said she wants an eventual reunification of the rival Koreas.
On Tuesday, President Barack Obama welcomed Park at the White House, declaring that North Korea can no longer create an international crisis with nuclear provocations.
Obama said the US and South Korea are fully capable of defending themselves against the North.
"The days when North Korea could create a crisis and elicit concessions, those days are over," Obama said after he met privately in the Oval Office with Park.
The US and South Korea are marking the 60th anniversary of forging their bilateral alliance, and are fresh from the most strident round of North Korean threats against them for many years.
Al Jazeera's Patty Culhane, reporting from Washington DC, said that the entire purpose of this visit was for the White House to send a message of solidarity with South Korea.
Park and Obama met hours after North Korea's military launched its latest threat, pledging to turn border islands into a "sea of flames" if a shell fell on its side during joint US-South Korea drills.
"If Pyongyang thought its recent threats would drive a wedge between South Korea and the United States or somehow garner the North international respect, today is further evidence that North Korea has failed again," Obama said.
But tensions have appeared to subside since earlier this year when North Korea carried out its third atomic test and vowed to prepare for nuclear war against the US.
North Korea moves missiles
In its latest provocative decision, North Korea has taken two Musudan missiles off launch-ready status and moved them from their position on the east coast.
Al Jazeera's Culhane said officials have been playing down the significance of the North's move.
She said analysts are saying that it is too early to decide whether this provocation cycle is up, down or zigzagging.
Follow coverage of escalating threats in Northeast Asia
A US defence official said on Monday that US did not believe the Musudan missiles had gone to an alternate launch site and that they were now believed to be in a non-operational location.
George Little, Pentagon spokesman, noted the change in North Korea's words, saying on Monday the "provocation pause" was a positive development.
"I wouldn't again comment on intelligence. But what we have seen recently is a 'provocation pause.' And we think that's obviously beneficial to efforts to ensure we have peace and stability on the Korean peninsula," Little said.
Amid dire threats and bellicose language from North Korea, two Musudan missiles had been deployed to the east coast, and the US and its allies Japan and South Korea had braced for a possible test-launch in the run-up to national celebrations on April 15.
A Musudan missile has an estimated range of roughly 3,000 to 3,500km, according to military officers.
North Korea has several hundred short and medium-range missiles available that could reach targets in Japan or South Korea, according to the Pentagon.