US Secretary of State Antony Blinken said on Thursday he and South Korea's foreign minister Park Jin share "profound" concerns about the growing military cooperation between North Korea and Russia.
Blinken and Park also said they discussed working together to implement a so-called extended deterrence strategy of countering threats from North Korea and furthering strategic cooperation with Japan.
"Already our three countries are taking steps to improve our joint response through real-time sharing of DPRK missile warning data, trilateral defense exercises and efforts to counter DPRK's malicious cyber activities."
DPRK, the Democratic People's Republic of Korea, is North Korea's official name.
From North Korea to Russia
The United States, South Korea and Japan have condemned what they say is the flow of arms and military equipment from North Korea to Russia, saying movements of cargo from the reclusive state to Russia was evidence.
Denial of claims
North Korea and Russia have denied any arms deals though their leaders pledged closer military cooperation when they met in September in Russia's far east.
Park also said after his meeting with Blinken the two foreign ministers urge the North to call off a plan to launch a spy satellite.
North Korea is preparing to launch a spy satellite after having failed twice this year to put one in orbit. South Korea said last week North Korea was in the final stages of preparations for a launch after apparently getting technical help from Russia.
South Korea's military said on Monday it was on alert after North Korea designated Nov. 18 as "missile industry day" to mark its launch of an intercontinental ballistic missile last year.
Blinken's two-day visit to South Korea is the first by a US secretary of state in two-and-a-half years and part of a broader Asia trip that will include a stop in India. He was in the Middle East before Japan.