Surprise and skepticism met the announcement that North Korea would freeze most nuclear activities in exchange for food aid from the United States.

U.S. Secretary of State Hillary Clinton said U.S. officials will closely watch North Korea carry out its promises to suspend uranium enrichment at its Yongbyon nuclear complex, stop long-range missile and nuclear tests and allow International Atomic Energy Agency inspectors to return.

Both sides call the steps confidence-building measures to improve relations between the U.S. and North Korea, and recognized the 1953 Korean War armistice as a "cornerstone" of peace on the Korean peninsula.

Some key questions and answers about the agreement announced late Wednesday:

Q: What is North Korea's motivation for reaching this deal?

A: Ensuring stability. As Kim Jong Un becomes the third-generation Kim to lead the nation, North Korea's leadership is keen to resolve potentially destabilizing issues, including the U.S. military presence in South Korea and chronic food shortages.

The Korean peninsula has been in a technical state of war since the Korean War ended in a truce in 1953, and a peace treaty with the U.S. is a key foreign policy goal for North Korea.

Food shortages in the country are chronic. Sanctions were imposed in 2006 and tightened in 2009 after two nuclear tests, and aid promised in exchange for disarmament was halted. That meant less food and resources, and harsh weather has also cut into the meager agricultural output.

The North Koreans would like to raise the issue of lifting those sanctions in future talks.

Q: What does this agreement say about Kim Jong Un's fledgling rule?

A: This deal is the clearest sign yet that the foreign policy laid out during Kim Jong Il's rule will be carried out under Kim Jong Un, and suggests a measure of stability and continuity in Pyongyang two months after his father's death.

After the provocations of 2009, including the launch of a long-range missile and a nuclear test, North Korea's foreign policy on the U.S. shifted dramatically in 2010. After Kim Jong Un was revealed during a special Workers' Party conference in September 2010 as his father's chosen successor, the policy toward the U.S. veered noticeably toward engagement and away from provocation.

Starting in July 2011, North Korean and U.S. diplomats met at least three times to hash out the details of a far-reaching agreement on offering food in exchange for nuclear concessions.

The Associated Press reported in December they were on the verge of signing the deal when Kim Jong Il's death put those negotiations on hold. That the North Koreans returned to the negotiations before the end of the semiofficial 100-day mourning period indicates unity within the new regime.

Q: What are North Korea's current nuclear capabilities?

A: North Korea tested nuclear devices in 2006 and 2009 and is believed to have enough weaponized plutonium for four to eight "primitive" atomic bombs, according to U.S. scientist Siegfried Hecker of the Center for International Security and Cooperation at Stanford University. In 2009, North Korea claimed it would begin enriching uranium, a second way to make atomic bombs, and revealed the facility to Hecker and North Korea expert Robert Carlin during a November 2010 visit. He says North Korea is not producing plutonium at the moment, but there's little information about whether they've made highly enriched uranium or tried to build a bomb using it.

Q: How effective will the agreement be in curtailing North Korea's nuclear capabilities?

A: Hecker says he has advised the U.S. government to think about three points: No more bombs, no better bombs and no exports. The suspension of uranium enrichment will limit its ability to make more bombs, while the moratorium means it won't be able to test its devices. U.N. inspectors are to be allowed back into North Korea's facilities to verify it is adhering to the agreement.

Q: Will North Korea ever rid itself of nuclear weapons?

A: Skepticism is widespread that North Korea will ever give up its nuclear weapons. North Korea has always cited the U.S. military presence in the region as a main reason for its drive to build atomic weapons, and having nuclear weapons to protect against the U.S. threat has always been a key source of pride for the North Koreans.

That said, North Korea insists that a nuclear-free Korean peninsula remains a goal.

Q: If this deal proceeds as expected, what will be the next step in improving relations between North Korea and the U.S. and its allies?

A: U.S. and North Korean officials must meet to discuss the technical details of distributing food aid, a tricky issue since Washington wants to be sure the food goes to malnourished children and not to the elite or the military. Next, North Korea must reach out to the International Atomic Energy Agency to allow the return of inspectors who were expelled in 2009.

The issue of tensions between the two Koreas, particularly blame for the deadly 2010 sinking of a South Korean warship, remains unresolved as does the matter of North Korea's abduction of Japanese citizens in the 1970s and 1980s. Both have been obstacles to resuming the six-nation nuclear disarmament talks that also involve China and Russia.

Q: How and when will the U.S. food aid arrive?

A: U.S. officials and non-governmental organizations say experts will have to be on the ground in North Korea before food delivery begins. Aid groups say that could take anywhere from several weeks to months. Washington and Pyongyang have promised another meeting "soon" to finalize details about a proposed initial package of 240,000 metric tons of food aid, with the potential for more down the road.

It may not, however, arrive in time for the big celebrations in April to mark the 100th anniversary of the birth of North Korea founder Kim Il Sung.

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Associated Press writer Foster Klug contributed to this report. Follow AP's Korea bureau chief Jean Lee at twitter.com/newsjean and Foster Klug at twitter.com/APKlug.