He warned the North, which has conducted missile and nuclear tests in defiance of United Nations sanctions, that the "era of strategic patience" was over.
As fears grow that it may also be preparing for its sixth nuclear weapons test, Vice Foreign Minister Han Song-Ryol said that its programme would only escalate.
Deputy Prime Minister Taro Aso said that the two countries would hold a new round of economic talks by the end of the year.
"The United States of America will always seek peace but under President Trump, the shield stands guard and the sword stands ready", Pence told 2,500 sailors dressed in blue fatigues and Naval baseball caps on a sunny, windy morning aboard the carrier at the U.S. Yokosuka naval base in Tokyo Bay.
The dialogue was set up by President Donald Trump and Japanese Prime Minister Shinzo Abe during the Japanese leader's visit to the U.S.in February.
Both sides said they do not expect the talks in Tokyo this week to delve into sector-by-sector talks on trade.
"It's necessary to put pressure on North Korea so that it will accept dialogue in good faith", Mr Abe said.
Pence arrived in Tokyo on Tuesday from South Korea, where he visited the heavily fortified border separating the North and South.
North Korea has accelerated its nuclear and missile tests in recent years, despite global condemnation and United Nations sanctions.
The United States was the most important participant, he said.
But now, Pence will try to reassure his jittery hosts that those decades-old security commitments are ironclad, a necessity made more acute after Washington's refusal to rule out military action against the regime.
At the outset of a working lunch with Abe, Pence said that the administration of U.S. President Donald Trump remained committed to working together with regional stakeholders to ensure a peaceful Korean Peninsular.
Secretary of State Rex Tillerson has had some choice words for Pyongyang since joining Trump's Cabinet, but North Korea has seemed eager to test the waters with the new administration by ramping up its military tests.
The US has been unnerved by North Korea's advancing missile and nuclear programs and has dispatched a military strike group to the Korean Peninsula.
"If the USA dares opt for military action", North Korea is "ready to react to any mode of war desired by the U.S.", he said.
"We will take the toughest counteraction against the provocateurs".
Former defense officials like Abraham Denmark believe that neutralizing test missiles would lead to an escalation that could possibly be deeply impactful for South Korea and Japan, two USA allies in the region.
"The Trump administration has not presented to the Congress a coherent policy in regards to North Korea", Cardin said on CNN's "Erin Burnett OutFront".
NAIJ.com recalls that the missile fired on Sunday, April 16, blew up nearly immediately. So it may not be altogether surprising that Trump doesn't know the name of the leader of North Korea, Kim Jong-un.
The military has not chose to intercept a test missile but the USA defense secretary James Mattis has briefed Congress on the option.
China also made a plea for a return to negotiations, with Foreign Ministry spokesman Lu Kang saying Beijing wants to resume the talks that ended in stalemate in 2009. "We are with you 100 percent", he said.