U.S. diplomatic efforts to address the nuclear crisis with North Korea faltered when Pyongyang in April tried to launch a satellite into orbit using a long-range rocket. Similar launches in 2006 and 2009 coincided with North Korean nuclear tests.
The April attempt upended a deal that saw Pyongyang declare a moratorium on long-range missile and nuclear tests in exchange for food assistance from the United States.
Jim Zumwalt, deputy assistant secretary of state for East Asian and Pacific affairs, told leaders of the House Subcommittee on Asian and the Pacific that he was frustrated with Pyongyang's actions but was committed to a policy of engagement.
"The United States is prepared to engage constructively with North Korea but its new leadership must understand that there will be no rewards for provocations," he said during the hearing.
Tensions on the Korean Peninsula have increased since the December death of North Korean leader Kim Jong Il. His son, Kim Jong Un, now leads the country.
U.S. and South Korean militaries conducted military exercises in the region in May.
"The United States is fully committed to the defense of the Republic of Korea, and we stand shoulder-to-shoulder in face of DPRK provocations," said Zumwalt.
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