American forces may have to focus the counterinsurgency skills they have gained in Iraq and Afghanistan on the threat posed by North Korea.

The American general leading US forces in South Korea told the South Korean military this week that "our enemies" are beefing up their guerilla warfare capabilities and would likely use improvised explosive devices and similar tactics if a ground war broke out.

Gen. Walter "Skip" Sharp said that means the South Korean military should prepare by conducting as much realistic training as possible – likely with the aid of the US.

"I believe we will face IEDs and insurgent forces in addition to large conventional attacks," said General Sharp in remarks there Tuesday. "We must immediately begin preparing both ROK [Republic of Korea] and US forces to improve our capabilities in these areas." Sharp didn't mention the "thinking enemy" by name until the end of his prepared remarks. "North Korea is watching and I am convinced that discussing and demonstrating the strength, capabilities, and leadership of the ROK army is the best deterrence."

Few experts envision an all-out ground war on the Korean peninsula. Yet they believe that countries taking on the US or its allies, if they are at a clear military disadvantage, are likely to begin to adapt the kinds of insurgent tactics effective in Afghanistan and Iraq.

Tensions have risen between North Korea and the international community as the nuclear-armed nation continues its saber-rattling and provocative rhetoric. This week, North Korea said it would "wipe out the aggressors on the globe once and for all" if the US began a war.

Meanwhile, the US Navy is tailing a North Korean cargo ship, the Kang Nam, suspected of carrying weaponry or materials forbidden under a UN Security Council Resolution passed earlier this month. The resolution does not authorize the US or another navy to forcibly board the ship – an act the North has said it would consider an act of war.

One of the North's few military strengths lies in its inventory of ballistic missiles. But the North does possess a reasonably effective special-forces component, says Victor Cha, a former member of the National Security Council under President Bush and now a senior advisor at the Center for Strategic and International Studies, a think tank in Washington.

"There is always concern that in some sort of situation like that, there could be a terrorist incident by special forces or the use of dirty bombs," says Mr. Cha.

Cha is doubtful that the North's military could create an insurgency of much note, since that would require it to push deep into the South to Seoul to have an effect. The North's use of insurgent tactics would likely be more conceivable if the South invaded the North, he said.