In an apparent show of force aimed at the Democratic People's Republic of Korea (DPRK), the US 7th Fleet announced the arrival of its USS Springfield to the South Korean port city of Busan.

"The Los Angeles-class fast-attack submarine USS Springfield (SSN 761) pulled into port in Busan, Feb. 23," the fleet said via their Twitter account.

The Los Angeles-class fast-attack submarine USS Springfield (SSN 761) pulled into port in Busan, Feb. 23. #USNavy #InternationalByDesign pic.twitter.com/kUZlqX6lX

— 7th Fleet (@US7thFleet) February 25, 2023

As part of the US navy's forward-deployed submarine force in the Indo-Pacific, there are routine port calls for Los Angeles-class submarines in South Korea. However, the stay of the USS Springfield, whose home port is in Guam, has not been revealed.

The Indo-Pacific Command noted earlier this week that it would continue to preserve its close ties with South Korea, especially in light of the DPRK's "recent aggressive nuclear policy and advancements in nuclear capabilities."

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DPRK may deem further US hostilities a 'declaration of war'

The US continued "hostile practices" toward DPRK, including possible military exercises and deployment of strategic weapons on the Korean peninsula, may be perceived as a "declaration of war" against Pyongyang, the Department of US Affairs of the DPRK  Foreign Ministry said on Friday.

After Pyongyang test-fired two ballistic missiles on Monday, Japan requested an extraordinary meeting of the UN Security Council (UNSC), according to Japanese Prime Minister Fumio Kishida.

"The U.S. should bear in mind that if it persists in its hostile and provocative practices against the DPRK despite the latter's repeated protest and warning, it can be regarded as a declaration of war against the DPRK. The U.S. should perceive intuitively and accept the consequences to be entailed by it," said Kwon Jong Gun, the department's director general, according to Korean Central News Agency (KCNA).

Kwon also protested the US and South Korea's actions, saying they "put a sovereign state's legitimate right to self-defense on the agenda of the UNSC."

"If the UNSC has a true intention to contribute to peace and security in the Korean peninsula, it will have to bitterly condemn the U.S. and South Korea for their moves of escalating military tension such as the frequent deployment of strategic assets and large-scale joint military drills against the DPRK," the official added.

Last week, the DPRK launched 2 ballistic missiles which could reach US rounds and test-fired two short-ranged ones toward Japan, which sparked security uneasiness in both South Korea and Japan. 

Japan announced that the missiles landed outside its exclusive economic zone. 

Read more: US, South Korea launch anti-DPRK nuclear drill over alleged threat