Osan Air Base, South Korea:
US Air Force fighter jets prepare to take off from a runway during their military exercise
The names of US-South Korean war games staged over the years don't sound all that threatening: Team Spirit, Ulchi Focus Lens, Key Resolve ... Foal Eagle. But whatever they're called, the annual show of force is guaranteed to get a rise out of North Korea.
Two decades ago, Kim Il Sung, the late founder of the still-ruling Kim dynasty, reportedly shook with rage while talking about the drills with a visiting US congressman. This year's drills, however, are unusual in the level of fury they've inspired from the North - Pyongyang has threatened nuclear war - and in the tougher-than-usual US response that some call a case of Washington overplaying its hand.
In late March, two nuclear-capable B-2 stealth bombers - among the war-fighting wonders of the world - took off from their Missouri base and flew more than 6,500 miles (10,400 kilometers) to drop dummy munitions on an uninhabited South Korean island before returning home.
"Heinous nuclear war rehearsal," the North's propaganda screamed.
If that reaction sounds over the top, consider the view from Pyongyang.
The Korean War ended in 1953 in a tenuous cease-fire, leaving the peninsula technically in a state of war that continues today. For a poor, inward-looking, fiercely proud, authoritarian nation that has long been spooked by its bloody history with the world's premier nuclear superpower, these weekslong springtime assemblies of thousands of allied troops and their gleaming jets, ships and submarines are clear proof that Washington and Seoul have Pyongyang in its crosshairs.
At Osan Air Base, south of Seoul, evidence of America's firepower was on display this week as a procession of its finest military machines barreled down a long runway separated from a sun-sparkling stream by a razor wire-topped fence. F-16 and A-10 jets, helicopters, a C-130 cargo plane powered up into the sky, banking over brown dirt fields, one-story Korean-style houses, dingy squat apartment buildings and long rows of crops covered with plastic to protect from a strong, cold early-spring wind.
Year after year, the allies call the exercises defensive and routine. And year after year, Pyongyang predicts they're preparations for an invasion aimed at overthrowing its leadership. This year's current Foal Eagle exercises, however, have seen the animosity spike.
The United States in March made a calculated decision to show North Korea that a wave of threatening rhetoric - feverish even by Pyongyang's standards, and linked to the drills and to UN sanctions in early March aimed at punishing North Korea for its latest nuclear test - would be met with strength.
Washington made the unusual announcement that the drills would include appearances by both the B-2s and B-52s, the nuclear-capable bombers that have a long and - from the North Korean perspective - menacing history on the Korean Peninsula.
"Clearly, it was intended to send a message," Gen. Herbert "Hawk" Carlisle, the top US Air Force commander in the Pacific, said in an interview, referring to the B-2s.
North Korea has since issued a string of threats notable for both their violence and specificity, including intensified warnings of missile attacks on US targets in the Pacific, the US mainland and South Korea.
And while North Korea's nuclear and missile capabilities are still thought to be inadequate to back up its threats to nuke the United States or even to send missiles to the US mainland, there is growing worry that a localized skirmish of the kind that happens with some frequency between the Koreas could escalate into something worse. There's also suspicion among officials in Seoul that North Korea is gearing up for a missile test.
A quieter US approach to the joint military drills would have sent the deterrence message Washington wanted "to warn the North Koreans to not walk too close to the edge of chaos. Instead, in the desire to impress the ally (South Korea) that we had their back covered, we decided to escalate the threat symbolism" with the B-2 and B-52 bomber flights, said Peter Hayes, who heads the Nautilus Institute, an Asia-focused think tank.
This escalation has set back by many years previous "hard work to devalue nuclear weapons and to get rid of nuclear fantasies as a solution to insecurity on the part of either Korea," Hayes said in an email.
The United States is now back-peddling - although the drills will continue until the end of the month. Reporters have been kept from exercises, and Washington delayed an intercontinental ballistic missile test amid the growing tensions.
Both sides conduct military drills because they're the best way to prepare for war, short of actual fighting. The US-South Korean drills are meant to deter North Korea from an attack like the one that started the Korean War in 1950.
But there's also a strong political element.
Skillfully done drills "can serve as a show of force to extract concessions from adversaries without having to resort to direct military intervention," former US Air Force officer John Farrell wrote in a 2009 case study of the exercises.
The biggest of the drills, Team Spirit, ran from 1976 to 1993, reaching a peak in the late '80s, with more than 200,000 people participating, according to Farrell. North Korea hated the drills, and they may have stoked tensions before an encounter in 1976 between Americans and North Koreans that still resonates today.
That August, North Koreans used axes to beat to death two Americans pruning a poplar tree in the Demilitarized Zone between North and South Korea. A furious United States responded with a massive show of force, sending B-52 bombers barreling up the southern half of the peninsula toward the DMZ, only to veer off at the last moment, according to Hayes.
North Korean officials in the 1980s began ordering their soldiers and citizens to assume a "war footing" when Team Spirit took place, Farrell writes. This proved expensive as the impoverished North spent precious resources to move equipment and troops to respond to the drills.
Reading North Korean intentions has proven more difficult than usual under Kim Jong Un, a young leader who has only been on the job since his father, Kim Jong Il, died in late 2011. The current rhetoric, however, does seem to fit a cyclical pattern in which North Korea raises fears among its adversaries before turning to diplomacy meant to win aid.
North Korea knows that its threats won't make the allies end their drills, said Andrei Lankov, a professor at Kookmin University in Seoul. Instead, it's largely an excuse to build tensions, mostly for "an aid-maximizing strategy" aimed at scaring donors into providing food and money.
Still, the combination of massive, stirred-up North Korean military and artillery forces poised along the border, only an hour's drive from Seoul, and thousands of US and South Korean troops conducting nearby drills has raised worries that a miscalculation could escalate into a broader conflict.
"The desire to show strength, the fear of looking weak and the presence of tons of hardware provides more than enough tinder that a spark could start a peninsula-wide conflagration," Patrick Cronin, a former official in the George W. Bush administration now with the Center for a New American Security think tank, wrote on Foreign Policy's website. A stray missile or a shooting in disputed waters "could trigger an action-reaction cycle that could spiral out of control if Pyongyang, running out of threats or low-level provocations, were to gamble on a more daring move."