Moscow, July 27 (IANS) Russia is concerned about a recently announced guideline between the United States and South Korea on joint nuclear planning, the media reported on Saturday, citing Russian Foreign Minister Sergei Lavrov.

"Another worrying aspect is that the United States has recently concluded an agreement with South Korea on joint nuclear planning," Russia's RIA Novosti news agency reported quoting Lavrov.

Russia has not yet received an explanation regarding the guideline, Xinhua news agency reported.

Lavrov added, "We have no doubt that it causes additional anxiety."

US and South Korean leaders authorised the guideline on July 11, which "provides guidance to Alliance policy and military authorities in maintaining and strengthening a credible and effective nuclear deterrence policy and posture," according to the White House.