A North Korean soldier in July 2012 photographs U.S.and South Korean soldiers on the opposite side of the Military Demarcation Line of the Demilitarized Zone that divides the two Koreas. A member of the Neutral Nations Supervisory Commission urged the two Koreas on March 13, 2013, to bring the rhetoric down.

SEOUL — The U.S. and South Korea signed a contingency plan Friday that gives South Korea both U.S. support and the lead in responding to future North Korea provocations.

The plan is apparently meant to address what one South Korean official described as small-scale “local” North Korean attacks such as the November 2010 shelling of Yeonpyeong Island, which prompted defense officials to begin developing the Counter-Provocation Plan. That attack on the South Korean border island left four people, including two civilians, dead.

However, a statement released by U.S. Forces Korea offered little information about the contingency plan, including what constitutes a “provocation.” The definition is important because the top U.S. general in South Korea currently would lead allied operations should war break out with North Korea.

“By completing this plan, we improved our combined readiness posture to allow us to immediately and decisively respond to any North Korean provocation,” the statement said. “The completed plan includes procedures for consultation and action to allow for a strong and decisive combined ROK-US response to North Korean provocations threats.”

USFK did not say why the plan had been developed or why South Korea will lead the response to any future provocations.

A spokesman for South Korea’s Joint Chiefs of Staff said the contingency plan does not affect U.S. wartime operational control, though he could not specify when an attack will be considered local and when it will rise to the threshold of war.

“It’s hard to answer this,” he said. “On our end, if there is a local provocation on our land, we have to respond to it.”

He said the increasing seriousness of North Korean attacks prompted the chairmen of both countries’ Joint Chiefs of Staffs to begin considering how to respond to other acts of aggression following Yeonpyeong. North Korea is believed to have torpedoed a South Korean warship in March 2010, killing 46 sailors on board, though Pyongyang denies involvement in the incident.

North Korea in recent weeks has increased its rhetoric against Washington and Seoul, threatening to turn both into a “sea of fire” following its third nuclear weapons test and the launch of a three-stage rocket.

Speculation has been widespread that the North may undertake some kind of provocation after the current exercises end as a test for South Korea’s new president. However, the JCS spokesman said his country believes the prospect of a joint U.S.-South Korean response to a localized attack will be a deterrent to the North.

On Thursday, the two countries ended the joint Key Resolve exercise, which was the first to be led by the South Korean Joint Chiefs of Staff and not the U.S.-led Combined Forces Command. The two-week exercise was essentially a dry run for the planned transfer of wartime operation control from the U.S. to South Korea, now scheduled for 2015.

The planned OPCON transfer has been a hot topic of debate in Washington and Seoul for years, given the threat posed by North Korea and varying opinions about whether the South’s military is up to the task of leading the fight should hostilities resume on the peninsula.

The JCS spokesman said the Counter-Provocation Plan signed on Friday was not releasable because of ongoing security concerns with North Korea. USFK did not respond to a request to provide a copy of the plan.

Stars and Stripes staffers Jon Rabiroff and Yoo Kyong Chang contributed to this report.

rowland.ashley@stripes.com