Russia's top diplomat said on Thursday that nuclear negotiations between the U.S. and North Korea remain deadlocked because of the U.S.' approach of trying to denuclearize the North "all at once."

Russia's Foreign Minister Sergey Lavrov made the remark during a joint press conference in Moscow after meeting with his Malaysian counterpart Saifuddin Abdullah. 

Lavrov said that Russia and China proposed a plan for the North's denuclearization in 2017, urging relevant parties to build trust, suspend military actions and nuclear and missile launches and seek dialogue. 

The minister said that in spite of summits between the leaders of North Korea and the U.S., bilateral contacts have been stalled lately and the reason is "very simple."

He said that North Korea believes that it has taken many substantial steps that deserve reciprocal moves. Meanwhile, the Americans think that they need to address all the issues "all at once" and are pondering how to encourage North Korea to do so as well.