South Korea said Monday it was "closely watching" for any signs of an imminent North Korean missile test after Pyongyang reportedly issued a no-sail zone off its east coast.

The South's Yonhap news agency had quoted a government source on Sunday as saying the North had imposed the no-navigation zone off the coastal city of Wonsan from November 11 to December 7.

South Korean President Park Geun-Hye said Friday she would be willing to hold a summit with North Korean leader Kim Jong-Un, but only if there was a "breakthrough" on Pyongyang's nuclear program.

In written answers to questions submitted by foreign news agencies, Park also warned Japanese Prime Minister Shinzo Abe against dragging his feet over a settlement for Korean women forced to work in Japanese military brothels during World War II.

North Korea announced Friday it would convene a congress of its ruling Workers' Party for the first time in 35 years, reviving a forum last gathered under the rule of current leader Kim Jong-Un's grandfather, Kim Il-Sung.

The congress -- only the seventh since the official founding of the party in 1945 -- will be held in May next year, the party central committee's politburo said in a statement carried by the North's official KCNA news agency.

President Park Geun-Hye vowed Tuesday to strengthen South Korea's defense capabilities -- backed by a defense budget hike -- to guard against future provocations from North Korea.

At the same time, she said Seoul would try and work with Pyongyang to increase the frequency of family reunions for those separated by the 1950-53 Korean War.

North and South Korean families divided since the Korean War said a tearful final farewell Monday, wrapping up a rare reunion that was clouded at the last by a maritime border spat.

After three emotionally fraught days seeking to redress more than 60 years of separation, the reunion ended on the most traumatic note of all -- a goodbye that for most of the elderly participants marked the last time they will ever see each other.

South Korea fired warning shots at one of the North's patrol boats as it strayed across the border, Seoul's defense ministry said, raising tensions while a rare reunion for families separated by the peninsula's 1950-53 war was underway.

The South's navy were launching a crackdown on Chinese fishing boats illegally operating off the country's western coast Saturday when it spotted the patrol vessel and fired five warning shots.

North and South Korean families were forced to say a final, traumatic farewell Thursday after meeting for the first time in more than 60 years, as the joy of temporary reunion gave way to the grief of permanent separation.

On the third and last day of their all-too brief, emotionally charged reunion in a North Korean mountain resort, the families were given two hours in the morning to say their last goodbyes.

Around 400 elderly South Koreans met privately Wednesday with North Korean relatives they haven't seen for more than 60 years, on the second day of a highly charged reunion for families torn apart by the Korean War.

In contrast to the previous day when their tearful and, in some cases, clearly traumatic meetings were played out in front of TV cameras, they were allowed two hours in their own rooms to try to bridge the decades of separation.

North and South Korea on Monday moved a step closer to a rare reunion for families separated for decades by the Korean War by exchanging a list of candidates for the event this month.

Red Cross officials from both sides met in the border truce village of Panmunjom and exchanged the list after ensuring candidates still have living relatives on the other side, the South's unification ministry said.

North Korea's foreign minister told the United Nations on Thursday that a peace treaty was urgently needed to prevent a repeat of the military standoff that rattled Asia two months ago.

Tensions soared on the Korean peninsula in August following a rare exchange of cross-border fire that also saw North Korean leader Kim Jong-Un put his frontline troops on war-footing.