Pence is on the first stop of a four-nation Asia tour meant to show America's allies, and remind its adversaries, that the Trump administration was not turning its back on the increasingly volatile region.
"Just in the past two weeks, the world witnessed the strength and resolve of our new president in actions taken in Syria and Afghanistan", Pence said in an appearance with Hwang.
Pence's visit came amid heightened tensions that have included North Korea attempting - and failing - to launch a missile in a test Saturday, and the U.S. Navy sending an aircraft carrier and accompanying ships to the region. On Thursday, the USA military said it had dropped "the mother of all bombs", the largest non-nuclear device it has ever unleashed in combat, on a network of caves and tunnels used by Islamic State in Afghanistan. Later Monday, South Korean prosecutors were expected to indict former president Park Geun-hye on corruption charges, providing for headline-grabbing news.
Trump wrote Sunday on Twitter that China was working with the United States on "the North Korea problem".
Pence said the United States will continued deployment of the THAAD missile defense system and "evolve a comprehensive set of capabilities to ensure the security of South Korea", vowing to "meet any use of conventional or nuclear weapons with an overwhelming and effective response".
"The era of "strategic patience" is over", he said, echoing similar comments by Secretary of State Rex Tillerson last month.
Pence's visit to the tense DMZ dividing North and South Korea came at the start of a 10-day trip to Asia and underscored USA commitment.
A USA armada, including an aircraft carrier and multiple warships, has been deployed to the Korean Peninsula.
North Korea's Deputy Foreign Minister Han Song-ryol told the BBC that an "all out war" could result if the USA took military action.More news: What Taxes Will You Pay in Retirement?
China has reiterated its call for North Korea to stop all tests, and has also called for a peaceful solution.
Defying worldwide pressure, the North on Sunday tried to test-fire another missile in an attempt that failed, but which fuelled fears that it may be preparing for its sixth atomic weapons test.
Even though coal imports from North Korea appear to have been cut, and Air China cancelled some direct flights from Beijing to Pyongyang from this week, overall imports and exports between the two countries were up sharply in the first quarter of this year, data released by Chinese customs showed.
Her response reflected the phrasing of North Korean propaganda, as well as the reality that every person here has heard talk of war for decades.
Pyongyang insists it needs a powerful arsenal - including atomic weapons - to protect itself from what it says is the ever-present threat of invasion by hostile USA forces.
North Korean officers wait for a military parade marking the 105th birth anniversary of the country's founding father Kim Il Sung to begin in Pyongyang, North Korea at the weekend.
Chinese Foreign Ministry spokesman Lu Kang told reporters in Beijing on Monday that the Korean peninsula was "highly sensitive, complicated and high risk" and that all sides should "avoid taking provocative actions that pour oil on the fire".
"This is a very risky path", Russian Foreign Minister Sergei Lavrov said at a news conference in Moscow. Its latest missile test on Sunday failed a few seconds after launch. But at the same time, McMaster said on "This Week" on ABC that "it's time for us to undertake all actions we can, short of a military option, to try to resolve this peacefully". "An abandonment of its nuclear weapons program and its ballistic missile program".
He said the United States insists "on the gangster-like logic that its invasion of a sovereign state is "decisive, just and proportionate" and contributes to "defending" the global order in its bid to apply it to the Korean peninsula as well".