He said he wasn't speaking for the U.S. administration, which keeps stressing that before the nuclear negotiations can restart, it needs to see actions and not just words from the government of young leader Kim Jong Un to show it is committed to the goal of denuclearization it agreed to in 2005.
"Washington's position is that it's not ready to come back to the negotiating table until North Korea demonstrates a somewhat more credible approach. Since they (North Korea) have been the ones that destroyed last year's agreement, it's up to them to create the conditions to show they are serious," Bosworth said.
The six-party process aims at dismantling North Korea's nuclear program in exchange for economic assistance, but the North withdrew from the talks in 2008 and has since conducted two nuclear tests and launched a three-stage rocket into space, moving closer to having an atomic weapon that could threaten America.
While the North's benefactor, China, is keen to restart the talks, the U.S. is likely looking for the North to first declare the kind of nuclear freeze and moratorium on tests prescribed in last year's failed "Leap Day" agreement.
Bosworth said the North Koreans didn't signal readiness to offer the Leap Day terms again, but it did not rule it out either. "They are still trying to sort out where they are and where they want to go," he said.
Advocates of engagement say negotiations are needed to slow North Korea's nuclear development that has continued apace despite tighter sanctions. But there are few champions in Washington for talking with the Kim regime, particularly following its threats this year of nuclear war. The administration is also swamped in high-stakes and politically risky diplomacy on Iran nuclear program, Syria's chemical weapons and the Israel-Palestine conflict.
U.S. Secretary of State John Kerry, however, indicated last week the door for negotiations with the North remains open.
"We are prepared to have a peaceful relationship with North Korea, we are not engaged in regime change, we are prepared to sign a non-aggression agreement - providing North Korea decides to denuclearize and to engage in legitimate negotiations to achieve that end," Kerry said during a visit to Japan.
In Berlin, the North Koreans outlined ideas on how denuclearization could unfold in phases, in exchange for progress on political, military and economic concerns, said former State Department official Joel Wit. "It's very preliminary but it shows they are thinking about how denuclearization could happen," he said.
To get talks started, the North Koreans said they are willing in the early stages to build confidence with a moratorium on nuclear tests and long-range missile tests, although not on space launches. North Korea says such launches are peaceful, but the U.S. regards them as a pretext for developing ballistic missile technology, violating a U.N. ban.
Another sticking point is whether the North, which has enshrined the drive to build a nuclear arsenal in its constitution this year, is willing to freeze production of plutonium and uranium and allow international inspectors in.
The North is already thought to have enough plutonium for between four to eight crude weapons, and according to South Korean intelligence recently restarted a mothballed reactor that can produce another bomb's worth a year.
Former U.S. official Evans Revere, who joined earlier informal talks in Beijing, said nothing he has heard from North Korean officials indicates readiness to pursue denuclearization. He said the North links its own disarmament to the U.S. withdrawing its nuclear weapons' "umbrella" protecting South Korea and Japan.
"I don't see Washington falling over itself to get back to the negotiating table," he said.
