SEOUL, South Korea -- On Saturday, the U.S. aircraft carrier Ronald Reagan completed a naval exercise in the Philippine Sea with South Korea. This was amid indications that North Korea may be preparing for its first nuclear test since 2017.

The three-day exercise, which began Thursday in international waters just off Okinawa, was the first joint drill between the allies and an American aircraft carrier since November 2017.

The Ronald Reagan joined the USS Theodore Roosevelt, Nimitz and participated in a rare trio-carrier exercise alongside South Korean naval vessels. This was during North Korea’s last provocative run of nuclear and intercontinental missile testing.

This latest drill was conducted weeks after President Joe Biden met with South Korean President Yoon Suk Yeol to discuss ways Washington can protect its ally against growing North Korean threats.

According to the U.S. Navy 7th Fleet, the exercise was meant to strengthen interoperability between the two navies.

Sung Kim, Biden's special representative for North Korea, stated that Washington was "preparing for all contingencies" and working closely with South Korea as well as Japan to monitor North Korean arrangements for possible nuclear tests.

Kim was in Seoul to attend a trilateral meeting of his South Korean, Japanese and Japanese counterparts. The purpose of the meeting was to discuss the nuclear standoff between North Korea and North Korea.

The North's next test will be its seventh since 2006, and its first since September 2017, when it claimed that it had detonated an intercontinental ballistic missile-compatible thermonuclear weapon.

Since 2019, nuclear negotiations between Washington, Pyongyang and Iran have been stalled due to disagreements over exchanging crippling U.S. sanctions for North's disarmament.

North Korea has conducted 17 missile tests this year, including the first ICBM demonstrations for nearly five years.