The United States says it has flown bombers over the Korean Peninsula and carried out a test of its anti-missile system.
In the latest show of military might to North Korea, the United States has flown two B-1B bombers over the Korean Peninsula.
At the same time, it has conducted what it calls a successful test of its missile-defence system known as THAAD.
The US Missile Defense Agency has announced a medium-range ballistic missile was launched over the Pacific and the THAAD system, based in the state of Alaska, shot it down.
That comes amid heightened tensions with North Korea, which conducted its own missile test late last week.
North Korea's launch involved a long-range missile reportedly capable of reaching the US mainland.
It was the second test of a long-range intercontinental ballistic missile by North Korea in a month.
US vice president Mike Pence has called the North Korean provocations "unacceptable" and says his country will step up global pressure to end North Korea's nuclear program.
"The era of strategic patience is over. The President of the United States is leading a coalition of nations to bring pressure to bear until that time that North Korea will permanently abandon its nuclear and ballistic-missile program."
US ambassador to the United Nations Nikki Haley has tweeted a similar message on Twitter.
Ms Haley says the United States is "done talking about" North Korea and is urging its neighbours China and South Korea to do more.
South Korea, however, is already acting, announcing it will begin talks with the Trump administration to strengthen its own missile program.
Newly elected South Korean president Moon Jae-in has called for the relaxation of limits on his country's missile arsenal.
Meanwhile, the North, or Democratic People's Republic of Korea, has issued a warning to the United States via state news television KRT.
"If the US fails to come to its senses and continues to resort to military adventure and 'tough sanctions,' the DPRK will respond with its resolute act of justice, as already declared." (Korean ...)
A day after the North Korean missile test, US president Donald Trump also took to Twitter to criticise China.
In his tweets, the President said he is "very disappointed" in China, adding it has done nothing for the United States with regards to North Korea.
But former Chinese diplomat Victor Gao has told the BBC Mr Trump's Twitter outbursts are doing little to calm tensions.
"I think the United States should not make itself into a spoilt child. The United States should handle itself in a high level of responsibility and engage countries like China in a very constructive way, treating China as an equal, rather than someone to be lectured about, and that will be the solid foundation where joint efforts can be made to achieve the ultimate goal of denuclearisation."
China, the North's main ally, says it opposes North Korea's missile launches, but it has also warned the United States to stop its deployment of THAAD in South Korea.
Early in his presidency, Donald Trump met with Chinese president Xi Jinping, urging China to use its economic clout to curb North Korea's nuclear ambitions.
But Mike Pence says China has not acted on the President's request.
"We believe China should do more. I think the President has been clear about that in his conversations with President Xi, that, while China has taken unprecedented steps to isolate North Korea economically and to bring diplomatic pressure, we believe China has a unique relationship with the regime in North Korea."
