The U.S. State Department says significant issues remain to be addressed following the second round of high-level talks with North Korea that ended in Geneva on Tuesday.

Department spokeswoman Victoria Nuland told reporters on Tuesday that Washington believes the two-day meeting was “constructive,” and “all the issues were covered.” She added that while some differences were narrowed, the two sides didn't realize any breakthroughs and significant issues remain to be discussed.

Nuland said now the U.S. is going to evaluate what it has heard from the North during the latest talks. She added that the U.S. and the North have agreed to be in touch at “an appropriate moment” and to hold contacts if deemed necessary through the New York channel.

On the stalled six-way nuclear talks, Nuland said that first, the dialogue between South and North Korea needs to continue and second, the North needs to take concrete steps on its nuclear obligations.