North Korean Foreign Minister Choe Son-hui has departed for Russia, Pyongyang's state media reported Sunday, amid deepening ties between the two countries. Choe left Pyongyang the previous day on her official plane to visit Russia at the invitation of her Russian counterpart, Sergei Lavrov, according to the Korean Central News Agency (KCNA). It did not disclose further details, including the purpose of the visit or her itinerary. Russia's foreign ministry announced Saturday (local time) that Choe had arrived in Moscow for an "official visit," without revealing other details. It marks Choe's first trip to Russia since October, when she visited Moscow on a "working visit" and Belarus to attend a global security forum. Speculation has arisen that Choe is visiting Moscow to coordinate North Korean leader Kim Jong-un's potential trip to Russia, given the absence of major diplomatic events or anniversaries between the two countries. North Korea and Russia have been deepening their ties since Kim and Russian President Vladimir Putin signed the "comprehensive strategic partnership" treaty in June