Three North Korean citizens on a small wooden fishing boat have returned back home Monday after mistakenly drifting into South Korean waters over the weekend.

The three North Koreans had a white mast on their boat, which might mean that they were defecting from the isolated Asian country. The three fishermen said that the white flag was used as protection.

The South Korean Defense Ministry did not believe the individuals were attempting to infiltrate South Korean territory and let them return home.

A similar event happened earlier this week, when North Korea released a detained Russian fishing boat that was carrying 15 Russians and two South Koreans.

North Korea-South Korea relations are tense, as Seoul is slated to carry out joint military exercises with the U.S. next month. This has angered Pyongyang, which has said that the exercises could derail current North Korean-U.S. negotiations over its controversial nuclear program.

President Donald Trump has met several times with North Korean leader Kim Jong Un to get North Korea to denuclearize in exchange for reduced sanctions, though no concrete deal has been reached.

North Korea sees the exercises as preparation for an invasion of its territory.

North and South Korea are still technically at war since the Korean War ended in 1953 with a truce, not a peace treaty.