Secretary of State Antony Blinken speaks during a joint news conference with NATO Secretary General Jens Stoltenberg at the State Department in Washington D.C., June 18. AP-Yonhap

U.S. Secretary of State Antony Blinken condemned growing military cooperation between Russia and North Korea and reaffirmed the "vital" importance of the Seoul-Washington alliance during phone talks with his South Korean counterpart, Friday, according to his spokesperson.

The call between Blinken and Foreign Minister Cho Tae-yul came after Russian President Vladimir Putin and North Korean leader Kim Jong-un signed a "comprehensive strategic partnership" treaty on cooperation in defence and other areas during their summit in Pyongyang, Wednesday.

"The secretary condemned deepening military cooperation between the DPRK and Russia, including ongoing arms transfers that violate multiple U.N. Security Council resolutions, and reaffirmed the vital importance of the ironclad U.S.-ROK alliance in promoting peace, security, and prosperity around the world," Matthew Miller, the spokesperson, said in a statement.

ROK and DPRK stand for the official names of South Korea and North Korea, the Republic of Korea and the Democratic People's Republic of Korea, respectively.

Blinken thanked Cho for Seoul's continued support for Ukraine while the two sides agreed to continue working together to address the "complex and evolving" security challenges posed by the North, as well as to support peace and stability in the South China Sea, according to Miller.

This week's summit between Putin and Kim has been a major source of concern for both Seoul and Washington due to its implications for regional and global security. (Yonhap)