President says it will continue to stress ties to Japan and the South until North gets more serious about denuclearization than talk ‘based on a press release’

Barack Obama said on Sunday that he does not believe North Korea is sincere in its offer to halt nuclear tests if the US suspends military exercises with South Korea, and that Pyongyang would “have to do better than that”.

On Saturday, North Korea’s foreign minister, Ri Su Yong, defended his country’s right to maintain a nuclear deterrent and warned that Pyongyang won’t be cowed by international sanctions. He also said the North’s regime would not soon collapse.

“Stop the nuclear war exercises in the Korean peninsula, then we should also cease our nuclear tests,” he said.

Obama dismissed North Korea’s latest overture at a news conference Sunday with the German chancellor, Angela Merkel, in Hannover, Germany.

“We don’t take seriously a promise to simply halt until the next time they decide to do a test these kinds of activities,” the president said.

“What we’ve said consistently,” he continued, “is that if North Korea shows seriousness in denuclearizing the Korean peninsula, then we’ll be prepared to enter into some serious conversations with them about reducing tensions and our approach to protecting our allies in the region.

“But that’s not something that happens based on a press release in the wake of a series of provocative behaviors. They’re going to have to do better than that.”

Obama also said that until North Korea offers a “better” proposal, the US will continue to “emphasize our work with the Republic of Korea and Japan, and our missile defense mechanisms, to ensure that we’re keeping the American people safe and we’re keeping our allies safe”.

Ri’s made his remarks just hours after North Korea test-fired a ballistic missile from a submarine in its latest show of defiance as this year’s US-South Korea exercises wind down. “The escalation of this military exercise level has reached its top level,” he said. “As the other side is going for the climax why not us, too, to that level as well?”

The US state department said that in response to Saturday’s launch, it would limit the travel of Ri and his delegation to UN functions in New York, where they are attending a meeting on sustainable development. “Launches using ballistic missile technology are a clear violation of multiple UN Security Council resolutions,” it said in a statement.

Ri suggested on Saturday that if Washington and Seoul suspended military exercises, it could open the door to talks and reduced tensions.

“If we continue on this path of confrontation, this will lead to very catastrophic results, not only for the two countries but for the whole entire world as well,” he said.

“It is really crucial for the United States government to withdraw its hostile policy against the DPRK and as an expression of this stop the military exercises, war exercises, in the Korean Peninsula. Then we will respond likewise.”

North Korean officials have floated similar proposals in the past, but the US has insisted that the North give up its nuclear weapons before any negotiations. Pyongyang has argued that the US and South Korea, with which its war technically continues, have forced the North to develop nuclear weapons for self-defense.

The result has been a stalemate that Ri said put the peninsula at the crossroads of a thermonuclear war.

In Seoul, South Korea’s foreign ministry released a statement Sunday that called the North’s proposal “not worth considering”.

This year’s exercises are the biggest ever, involving about 300,000 troops. Washington and Seoul say they beefed up the maneuvers after North Korea conducted its fourth nuclear test, in January, which also brought a new round of tough sanctions by the UN down on Pyongyang’s head.

“If they believe they can actually frustrate us with sanctions, they are totally mistaken,” Ri said. “The more pressure you put on to something, the more emotionally you react to stand up against it. And this is important for the American policymakers to be aware of.”

Pyongyang has responded to the exercises with a series of missile launches and statements that the country has developed its long-range ballistic missile and nuclear warhead technologies, to the point that they now present a credible deterrent and could even be used against targets on the US mainland. Not all foreign analysts accept that claim.

Ri said the possibility of conflict has increased significantly this year because the exercises have taken on what Pyongyang sees as a more aggressive and threatening tone, including training to conduct precision “decapitation” strikes on North Korea’s leadership.