The following is a chronology of major events leading to the restoration of communication lines between South and North Korea on Tuesday, 13 months after the North unilaterally severed them in protest of anti-Pyongyang leaflets sent across the border by activists.

2020

June 4 -- North Korea threatens to scrap a military tension reduction deal with South Korea and shut down major exchange projects in anger over Seoul's supposed failure to stop activists from sending anti-Pyongyang propaganda leaflets into the communist nation.

June 9 -- North Korea unilaterally cuts off all communication lines with the South.

June 10 -- South Korea's unification ministry announces decision to revoke business permits granted to two North Korean defector groups for sending anti-Pyongyang leaflets across the border, accusing them of putting at risk the safety of people living in the border regions.

June 13 -- Kim Yo-jong, younger sister of North Korea's leader Kim Jong-un, says the North will take the "next action" against the South, adding its army has been given the authority to take "the next action against the enemy."

June 16 -- North Korea blows up an inter-Korean joint liaison office in its border town of Kaesong, sharply escalating tensions on the Korean Peninsula after near-daily threats to punish Seoul over anti-Pyongyang propaganda leaflets.

July 17 -- South Korea revokes the operation permits of two North Korean defector groups, saying their campaigns to send propaganda leaflets into the communist nation "gravely hindered" efforts toward unification.

Sept. 22 -- North Korea fatally shoots a South Korean fisheries official who was adrift on its side of the Yellow Sea and burns his body. The official went missing the previous day while on duty near the western border island of Yeonpyeong.

Sept. 25 -- North Korean leader Kim Jong-un apologizes for the killing of the South Korean citizen by its military.

Dec. 14 -- South Korea's parliament passes a controversial bill prohibiting the sending of anti-Pyongyang leaflets across the inter-Korean border amid criticism the law violates freedom of expression.

2021

March 21 -- North Korea fires two cruise missiles off the west coast, marking its first missile tests in about a year.

March 25 -- North Korea fires two short-range ballistic missiles into the East Sea in violation of UN Security Council resolutions, marking its first ballistic missile launches in about a year.

July 27 -- South and North Korea announce the restoration of cross-border communication lines as part of efforts to improve inter-Korean relations. (Yonhap)