U.S. Secretary of State John Kerry expressed hope Tuesday that Seoul and Washington will soon strike a deal on revising the two nations’ civilian nuclear cooperation.

After talks with his South Korean counterpart, Yun Byung-se, Kerry warned North Korea to halt a recent spate of rhetoric and actions, and vowed that the U.S. would defend itself and its allies South Korea and Japan from North Korean threats.

“I’m very hopeful ― and I think the foreign minister shares this hope ― that this can be resolved before the visit of President Park,” Kerry said, commenting on the bilateral nuclear cooperation in a joint press conference.

President Park Geun-hye is scheduled to visit Washington in early May for a summit with President Barack Obama.

The two sides have had talks on revising the 40-year-old pact which expires in March next year. The gap between the two sides is wide despite two years of negotiations.

Seoul is seeking Washington’s consent to enrich uranium and reprocess spent fuel for peaceful purposes. Washington is concerned about the negative impact to its global nonproliferation drive.

Kerry’s remarks sparked speculation that the two countries might have made significant progress in their talks.

Standing next to Kerry, Yun was more cautious.

“I stressed to Secretary Kerry the importance of revising the Korea-U.S. civil nuclear cooperation agreement in a mutually beneficial, timely and forward-looking manner,” he said. “Both sides will continue consultations in this regard.”

Yun did not talk about any specific timeline.

South Korean officials later said it’s still too early to tell when the negotiations will end.

Later in Seoul, a senior Foreign Ministry official said formal negotiations will resume this month.

“Chief negotiators from the two nations are in the midst of preparing to resume formal negotiations,” he said. Asked when the talks would be reopened, the official replied, “within April.”

South Korea and the U.S. have not even held formal talks on the issue since the launch of the Park Geun-hye administration in February.

Park Ro-byug, South Korea’s chief negotiator, plans to visit Washington this month for talks with Robert Einhorn, who leads the U.S. negotiating team, according to a senior South Korean government official.

“Since we have to see how the talks will go, at this point it’s hard to say when the negotiations will be completed,” the official said.

The U.S. hopes to wrap up talks as early as possible and so does South Korea, he said.

“But what is more important is the content of the deal,” he stressed.

The meeting between Yun and Kerry came after North Korea ratcheted up an almost daily string of threats toward the three nations with an announcement that it would revive a long-dormant nuclear reactor and ramp up production of atomic weapons material.

Kerry said North Korea knows that the U.S. is fully prepared and capable of defending itself and its allies.

“The bottom line, very simply, is that what Kim Jong-un has been choosing to do is provocative, it is dangerous, reckless, and the United States will not accept the DPRK as a nuclear state,” Kerry said, referring to North Korea’s young, new leader.

A North Korean official said the country would quickly begin “readjusting and restarting” the facilities at its main Yongbyon nuclear complex, including the plutonium reactor and a uranium enrichment plant. It had been shuttered as part of international nuclear disarmament talks in 2007 that have since stalled.

Kerry said such a step would be “a direct violation” of North Korea’s international commitments and a “very serious step.”

“It would be a provocative act and completely contrary to the road we have traveled for all these years,” Kerry said.

Still, both Kerry and his South Korean counterpart said the door remained open for North Korea to return to multinational nuclear disarmament talks.

Yun said those talks remain a “useful tool” for getting North Korea to give up its nuclear weapons, although he conceded it would be a very difficult task. “We should continue these efforts,” he said.

“If North Korea decides to give up its nuclear ambitions and to become a member of the international community, we are prepared to resume talks” for peace on the Korean Peninsula, he said.

Yun said South Korean President Park Geun-hye is open to building a trusting relationship with North Korea but that Seoul would respond to provocations from Pyongyang. It was critical that the U.S. and South Korea continue to enhance their defense capabilities, he said.

(From news reports)