(NewsNation) — Presidents Joe Biden of the United States and Yoon Suk Yeol of South Korea on Wednesday will sign an agreement to have U.S. nuclear-armed submarines docked in the Asian country for the first time in 40 years.

This is Biden’s third bilateral meeting with Yoon, and it comes at a moment of heightened anxiety for both leaders over an increased pace of ballistic missile tests by North Korea over the last several months.

Congressional researchers wrote in a report that Yoon is hoping to transform South Korea into a “global pivotal state” by becoming a more active partner in the United States’ Indo-Pacific strategy.

Here’s a look at the relationship of the two countries so far:

Security

There are 28,500 U.S. Troops in South Korea, and it is one of the U.S.’ most important geopolitical and military-strategic partners. According to the Department of Defense, troops work with Korean forces daily, and the U.S. military and South Korean military are extremely interoperable.

Signed in 1953 at the end of the Korean War, the U.S.-Republic of Korea Mutual Defense Treaty commits the United States to helping South Korea defend itself — particularly from its neighbor to the North. South Korea has traditionally paid for about 50%, or over $800 million annually, of the total nonpersonnel costs of the U.S. military presence.

Although strained under former President Donald Trump, the Biden administration has worked to repair the alliance between South Korea and the U.S. The relationship between South Korea and the U.S. was so bad under Trump that Congress at the time imposed conditions on the former president’s power to withdraw troops from the country.

In 2021, the Biden administration concluded a cost-sharing negotiation with South Korea that boosted the country’s contribution to alliance costs by 13.9%.

Trade

South Korea is one of the United States’ most important economic partners in Asia. The economic relationship is bolstered by the U.S.-South Korea Free Trade Agreement, or KORUS FTA, which was implemented in 2012.

U.S. goods and services exports to South Korea totaled $95.5 billion in 2022, and imports were at $132 billion, according to the Congressional Research Service.

In 2022, South Korea was the United States’ seventh-largest trading partner for goods and services combined.

The relationship is reciprocal, though — in 2022, the U.S. was South Korea’s second-largest trading partner.

The Associated Press contributed to this report.