The US and South Korea have agreed to indefinitely suspend two exchange program training exercises, to support diplomatic negotiations with North Korea although US President Donald Trump cited "an unusual and extraordinary threat" from Pyongyangs nuclear arsenal. The US and South Korea have already announced the shelving of the large-scale Ulchi Freedom Guardian exercises slated for August, making good on a pledge by Trump during his summit with North Koreas leader. Fridays decision by the Pentagon followed a high-level meeting between Defense Secretary Jim Mattis, Secretary of State Mike Pompeo, Chairman of the Joint Chiefs of Staff Joe Dunford, and National Security Advisor John Bolton.  "To support implementing the outcomes of the Singapore Summit, and in coordination with our Republic of Korea ally, Secretary Mattis has indefinitely suspended select exercises," Pentagon spokeswoman Dana White said in a statement. Two Korean Marine Exchange Program training exercises scheduled to occur in the next three months have now been shelved. Despite the historic summit between Trump and North Korean leader Kim Jong Un, a presidential declaration sent to Congress on Friday explained why the administration would keep in place tough economic restrictions first imposed by former president George W. Bush. "The existence and risk of proliferation of weapons-usable fissile material on the Korean Peninsula and the actions and policies of the Government of North Korea continue to pose an unusual and extraordinary threat to the national security, foreign policy, and economy of the United States," it said. "I am continuing for one year the national emergency with respect to North Korea," added the statement. At their summit, Kim and Trump signed a pledge "to work towards complete denuclearization of the Korean Peninsula," a stock phrase favored by Pyongyang that stopped short of longstanding US demands for North Korea to give up its atomic arsenal in a "verifiable" and "irreversible" way. After flying back to Washington last week, boasting of success, the US leader tweeted: "There is no longer a Nuclear Threat from North Korea."