SEOUL (Reuters/AFP) - South Korean President Park Geun Hye said on Friday that the United States and South Korea had agreed to do what it takes to contain North Korean "provocations".
She was speaking after talks with visiting US President Barack Obama, who said North Korea will gain "nothing" by making threats.
"Threats will get North Korea nothing," Mr Obama said at a joint press conference Ms Park. "The United States and South Korea stand shoulder-to-shoulder in refusing to accept a nuclear North Korea," he added.
Additionally, South Korea and the United States have agreed that a 2015 date to transfer operational command of South Korean forces could be reconsidered after Seoul asked for a delay, Mr Obama told the press conference on. Seoul had pushed for a renegotiation of the agreement, fearing that Washington's security commitment to South Korea could have been weakened due to the transfer.
Seoul and Washington said in a joint statement that "due to the evolving security environment in the region, including the enduring North Korean nuclear and missile threat, the current timeline for the transition of wartime operational control (OPCON) to a Republic of Korea-led defense in 2015 can be reconsidered."
Satellite photos taken just two days ago showed additional activity at North Korea's Punggye-ri test site that is "probably related to preparations for a detonation", the US-Korea Institute at Johns Hopkins University said.
The report echoed recent warnings from South Korea that the North might be planning a nuclear test to coincide with Mr Obama's two-day visit.
In an interview ahead of his arrival in Seoul, the US President warned North Korea could expect a "firm response" if it made "the mistake" of conducting another nuclear test.
Earlier this week, Pyongyang slammed Mr Obama's visit as a "dangerous" move that would escalate military tension and bring the "dark clouds of a nuclear arms race" over the Korean Peninsula.
In March, the North warned it would not rule out a "new form" of nuclear test to boost its nuclear deterrent, after the United Nations Security Council condemned Pyongyang's launch of a mid-range ballistic missile into the sea east of the peninsula.
North Korea has been under UN sanctions since its first nuclear test in 2006, banning it from conducting atomic and missile tests, barring UN member states from weapons trade with Pyongyang and financial transactions that facilitate them.