"The experience of this close coordination in 2013 appears to have deepened the reservoir of trust between the two governments, to the point that the Obama Administration appears comfortable with letting Park take the lead in trying to encourage more cooperative behavior from Pyongyang:" "U.S.-South Korea Relations," Feb. 12, 2014.http://www.fas.org/sgp/crs/row/R41481.pdf
The two allies have completed a "Counter-Provocation Plan" for response to North Korean attacks such as those in 2010.
However, there may not be total agreement on the future of South/North relations. The report cites as an example potential US displeasure at South Korean consideration of increasing the nations involved in a key North Korean free trade zone. The CRS also details other sensitive issues, including South Korean re-processing of nuclear fuel and poor South Korean-Japanese ties.
Note: Current President Park is the daughter of Park Chung-hee, the dictatorial leader of South Korea from 1961 to his assassination in 1979. In recent years, many South Koreans have recalled the elder Park more fondly, despite human rights abuses during his tenure, due to his role in raising South Korea from poverty to economic success. You can see video of a 1974 attempt to kill Park here: