Timeline: From historic summit to building destruction, North Korea unsettles U.S.

WASHINGTON (Reuters) - North Korea on Tuesday blew up a building set up in 2018 in a border town as a joint liaison office to foster better ties with South Korea, the latest in a series of actions by Pyongyang that have increased concerns in Washington.

North Korea's hostilities have included missile tests and harsh rhetoric since an unprecedented summit between U.S. President Donald Trump and North Korean leader Kim Jong Un in Singapore in 2018. This has led to bouts of increased tension, though Trump - who once derided Kim as "Little Rocket Man" - has largely downplayed Pyongyang's actions.