The two sides also agreed to deal with North Korean nuclear problem with ”utmost urgency“ and “determination,” reflecting Seoul‘s push to turn Washington’s attention toward Pyongyang.

They also warned Pyongyang, saying it would face consequences as well as sanctions if it carries out missile or nuclear tests, while also opening doors for dialogue and assistance on the condition of it dropping its nuclear ambitions.

At a joint press conference that followed, Obama made it clear that the U.S. will engage in talks with North Korea only if it shows seriousness about denuclearization.

"As my administration has shown with Iran and with Cuba, we are also prepared to engage nations with which we have had troubled histories, but Pyongyang needs to understand it will not achieve the economic development it seeks so long as it clings to nuclear weapons," he said.

"Pyongyang's nuclear and missile programs have achieved nothing except to deepen North Korea's isolation."

The two also acknowledged Park’s Dresden address that envisaged a peacefully unified Korean peninsula by saying, “We will intensify high-level strategic consultations to create a favorable environment for the peaceful unification of the Korean peninsula.”

Standing alongside with Obama, Park said that North Korea and its leader needed to display "genuine willingness" to give up its nuclear program.

"North Korea has to come to its own conclusion that it is genuinely willing to give up nuclear capabilities and become a full-fledged member of international society," she added.

The two leaders adopted the new set of joint statements separately on North Korea for the first time, the presidential office said. A joint fact sheet was also given, redirecting the scope of bilateral cooperation into new fields of interests, such as space, welfare and cyber security.

"Today, I want to reaffirm that the commitment of the United States to the defense and security of the Republican of Korea will never waver,” Obama said.

"Our alliance remains a linchpin of peace and security not just on the Korean peninsula, but across the region, and so South Korea plays a central role in America's rebalance to the Asia-Pacific, and we continued that work today."

The news conference was held after their summit in Obama’s office, the Oval Office, and official lunch in the Cabinet Room.

Through the agreement reached with Obama, Park is expected to gain fresh momentum to push her North Korean agenda at a time when the two Koreas have revived high-level talks and are readying to hold a reunion of separated families next week. China addressing its concerns on North Korea’s provocations in last month’s summit with Obama was also seen to instill confidence in South Korea’s drive to bring Pyongyang back to the negotiation table.

Also, the summit was seen as a watershed moment for Park and her diplomacy as she strived to reaffirm the U.S. alliance and dispel pervasive speculation that Seoul is inclining toward Beijing.

Throughout her trip, Park has been hailing the alliance with the U.S., stressing their “dynamic and strong partnership” has evolved to a higher level and would remain unshaken in the future.

Overturning concerns, Obama said he doesn’t see any cracks in Korea-U.S. alliance. Obama said he also wants Seoul to build strong relationship with China, as well as the relationship between Washington and Beijing.

During an hour and a half meeting with Obama, Park also demonstrated her efforts to bolster regional cooperation in Northeast Asia by hosting a trilateral summit with Japan and China in November, and a summit with Japanese Prime Minister Shinzo Abe on the sidelines of the talks, a development that Washington has encouraged.

"The trilateral summit that President Park will host this month can be another step forward in building positive relations between South Korea, Japan and China," said Obama.

Before meeting Obama, Park sat down with Vice President Joe Biden at his residence on Thursday for a luncheon.

“The two discussed the importance of strong regional relations and close coordination on common strategic interests,” the White House said after the meeting.

It also said Biden praised Park for her efforts to improve inter-Korean ties and reaffirmed unwavering U.S. commitment to deter and defend against North Korean provocations.

Park was the first Asian leader invited to the vice president’s residence since the Obama administration was launched in 2009, Cheong Wa Dae said in a briefing, adding that the luncheon was an expression of the special alliance between the two countries.

Appealing for her vision of a unified Korea to opinion leaders in the U.S., Park stressed the alliance is crucial for pressing North Korea to drop its nuclear aspirations.

“I believe the Korea-U.S. alliance must exert our leadership in inducing North Korea to abandon its nuclear program, open up to the world and undertake internal reforms,” Park said in a speech at Washington-based think tank Center for Strategic and International Studies.

“A unified Korea will be a generator of peace. No longer will nuclear weapons and long-ranged missiles target our neighbors.”

By Cho Chung-un, Korea Herald correspondent (christory@heraldcorp.com)