Speaking at a news briefing in Beijing, Acting Assistant Secretary for East Asian and Pacific Affairs Susan Thornton said China understood that America viewed the North Korea situation as an urgent "time-limited problem set".
"The new government of the Republic of Korea will make effort toward solving this issue with the participation of all parties concerned", the diplomat said.
Shooting down the test rockets will accomplish two short-term goals: It will prevent North Korea from verifying its rockets' reliability and it will show China if it does not rein in its protégé state, the United States will not hesitate to take unilateral action.
She said Chinese officials say they've tightened border inspections, beefed up policing on the border and stepped up customs inspections.
"North Korea now is rebuffing overtures from China, which is frustrating China", she said.More news: Celtics' playoff hopes rest on LeBron James having another bad night
"Kim Jong Un is raising a new generation of people separate from his father's key aides", said a South Korean official with knowledge of the matter, referring to Kim Jong Il, who died in late 2011 leaving the younger Kim in charge.
China has signed on to United Nations sanctions and suspended coal imports from North Korea through the rest of the year, but has been generally reticent about what other steps it may be taking to use its leverage as Pyongyang's most important trading and diplomatic partner.
The academy runs North Korea's advanced weapons systems research and development, "including missiles and probably nuclear weapons", the U.S. Treasury said in 2010 in its decision to blacklist the group. It says the programme is necessary to counter USA aggression.
'So they know now that they don't have, I think, as much time to try to bring the North Koreans to the table to get their calculus changed and get them to the negotiating table, ' she said.
Last year, the government gave the green light only to Eugene Bell Foundation Korea, an global organization that specializes in providing tuberculosis medication to the impoverished country. Satellite imagery suggests it could be ready to conduct its next test - its sixth - at any time.More news: LeBron James tops Michael Jordan as all-time playoffs scoring leader
But he slammed a subsequent missile launch as a "reckless provocation". The regime's oft-stated goal is to ideal a nuclear warhead that it can put on a missile capable of hitting Washington or other US cities.
The US has a carrier strike group, the most powerful unit of naval power in existence, near North Korea's shores.
For South Korea, a more immediate danger may be the North's massed artillery, which could devastate parts of the capital Seoul, only 40 km (25 miles) from the border.
While her designation was met with cheers from younger diplomats who give her credit for her reasonable work style and "soft power" leadership, skeptics have pointed to her lack of experience in pressing issues such as North Korea, the security alliance with the USA, and China and Japan affairs. The US has deployed the world's most advanced missile-defense system to South Korea, to protect against ballistic missiles.More news: Bernie Sanders: Lieberman Would Be 'Very Contentious' FBI Director Nominee