On 26 March 2010, the 1500-tonne ROKS Cheonan sank with 104 men off Baengnyeong Island in the Yellow Sea. Seoul said there had been an explosion in the rear and that it was a torpedo attack. Out of 104 sailors, 46 died and 58 were rescued. South Korean President Lee Myung-bak convened an emergency meeting of security agents and ordered the army to focus on rescuing sailors.   On 20 May 2010, an international team of researchers published results claiming that the sinking was caused by a North Korean torpedo; North Korea rejected the results.  South Korea endorsed the research group`s findings and President Lee Myung-bak went on to say that Seoul would reduce overall trade with North Korea as part of measures aimed primarily at countering North Korea diplomatically and financially. [Citation required] North Korea denied all such allegations and responded by separating relations between the countries and announced that it would repeal the non-aggression agreement.  In 1994, concern about North Korea`s nuclear program led to the agreed framework between the United States and North Korea. In 1998, South Korean President Kim Dae-jung announced a policy of sunshine towards North Korea. An inter-Korean summit was held in 2000.
Persistent concerns about the development of nuclear missiles in North Korea led to the 2003 six-party talks, which were attended by North Korea, South Korea, the United States, Russia, China and Japan.  However, in 2006, North Korea resumed the missile test and conducted its first nuclear test on 9 October.  A second inter-Korean summit was held in 2007.  Until 2017, estimates of North Korea`s nuclear arsenal ranged from 15 to 60 bombs, probably hydrogen bombs. Analysts say the Hwasong-15 missile is capable of striking anywhere in the United States.  Militarist rhetoric has increased on both sides.  In preparation for US President Nixon`s visit to China in 1972, South Korean President Park Chung-hee began discreet contacts with Kim Il-sung of the North.  In August 1971, the first Red Cross discussions took place between North and South Korea.  Many of the participants were really secret service agents or party officials.
 In May 1972, Lee Hu-rak, the director of the Korean CIA, secretly met Kim Il-sung in Pyongyang. Kim apologized for the Blue House robbery and denied accepting it.  In return, North Korean Deputy Prime Minister Pak Song-chol made a secret visit to Seoul.  The North-South Joint Declaration was made public on July 4, 1972.