The statement also reiterated Washington's full commitment "to working closely with our allies", particularly South Korea and Japan, to maintain security.
U.S. Vice President Mike Pence has arrived in South Korea at the start of a 10-day trip to Asia that comes amid turmoil along the Korean Peninsula over North Korea's threats to advance its growing nuclear and defense capabilities.
The US has warned that a policy of "strategic patience" with North Korea is over. "We have submarines, very powerful, far more powerful than the aircraft carrier", said President Donald Trump to Fox Business Network on Wednesday.
In South Korea, there is no sign of tension either but also very little talk of war.
He arrived in South Korea shortly after a failed missile launch by the North that surrounded the birth anniversary of North Korea's late founder.
North Korea did some posturing of its own on Saturday, rolling out intercontinental ballistic missiles and other military hardware at a parade to celebrate the birthday of the country's late founder Kim Il Sung.
North Korea displayed its submarine-launched ballistic missile and the land-based version it launched last month as well as two new intercontinental ballistic missile-sized canisters as the military paraded down Kim Il Sung Square, analysts said.
But the North's Workers' Party of Korea Vice Chairman Choe Ryong-hae said in a speech Saturday that Pyongyang is ready to respond to the US with "an all-out war" including nukes. A report emerged this week that Trump is ready to launch a preemptive strike against North Korea if officials believe Pyongyang is going to go through with a nuclear weapons test, although several outlets questioned the report.
"The time for action is now and by that we need to look at ways to put increased pressure on North Korea in order for it to recognize the reality that it needs to pursue de-nuclearisation", State Department spokesman Mark Toner said on Thursday.
"Trump is always making provocations with his aggressive words", Han said.
The president and other senior officials have issued a series of ominous statements suggesting the USA could conduct a preemptive military attack on North Korean targets to prevent the regime from completing its quest to develop an ICBM that could threaten the United States with nuclear weapons.
However, John Bolton, America's former ambassador to the United Nations, said piling on pressure wouldn't work and that the USA needed China's help to try and bring North and South Korea back together.
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When Secretary of Defense James Mattis and Secretary of State Rex Tillerson traveled to Asia earlier this year, the principle objective was to reassure allies that the Trump administration would maintain the USA commitment to defend them.
China, North Korea's only backer, fears conflict could cause the regime to collapse and problems on its border.
That means the much-anticipated April 15 North Korean holiday has ended without any event that would trigger a possible US attack, and therefore, possible World War III.
Kim, wearing a suit and tie, was greeted Saturday with thunderous - and extensively practiced - applause as he stepped into view on a large podium, clapping to acknowledge the thousands of soldiers and civilians taking part in the parade at Kim Il Sung Square.