SEOUL (AFP) - North Korea's latest missile test has extended the range of its weapons to much of mainland US and raised new fears in the South: would Washington protect Seoul when that could put American cities in danger?
The US is security guarantor for the democratic and capitalist South, where 28,500 US troops are stationed to defend it from Pyongyang after the 1950-1953 Korean War ended with a ceasefire instead of a peace treaty.
The alliance with Seoul has also been a key pillar of Washington's geopolitical strategy in Asia, where China is increasingly flexing its muscles as it seeks military clout commensurate with its economic might.
But last week's intercontinental ballistic missile (ICBM) test put major US cities including Chicago and Los Angeles within range of a potential attack from the nuclear-armed North.
Now South Korean media and experts fear that could cast a cloud over US commitment to the alliance, long described as "rock solid" by both sides.
"Would the Trump administration protect us from an attack from the North when doing so could risk putting the US in danger of a nuclear attack?" JoongAng Ilbo, a major Seoul newspaper, said in an editorial.
It was only "a matter of time" before the North develops a fully operational, nuclear-tipped missile capable of hitting the US, it said.
And at that point, it concluded gloomily, the answer "may not be yes".
There remain doubts whether the North has mastered the technology needed for a missile warhead to survive re-entry into the Earth's atmosphere, or if it can miniaturise a nuclear weapon to fit into a nose cone.
But it claims to have done so and has undoubtedly made rapid technological advances since Kim Jong Un came into power in 2011, with the young leader overseeing three nuclear tests and a string of missile launches.
The North has for decades demanded the US sign a peace treaty with Pyongyang and withdraw its troops from the South.
Visiting US politicians always pledge that Washington is committed to the alliance - Vice-President Mike Pence, who toured the Demilitarised Zone that divides the two Koreas in April, called it "ironclad and immutable".
But South Korea's top-selling daily Chosun Ilbo questioned those reassurances following the ICBM test.
It was "hard to expect the US to help the South" if that risked a nuclear attack on America, it said in an editorial on Monday, and followed up with a Tuesday warning: "The worst-case scenario is US troops withdrawing from the Korean peninsula."
"That is what North Korea ultimately wants," it added. "For South Koreans who have grown used to decades of protection from the US Forces Korea, that prospect is almost unimaginable. But the reality is that things are heading in that very direction."
At the same time, South Koreans fear the possibility of a preemptive strike by the US against the North, which could trigger devastating consequences even without Pyongyang resorting to nuclear weapons.
It has massed conventional artillery within range of Seoul, which could inflict catastrophic damage on the capital before being neutralised.
The US has hardened its stance on the North since Friday's test, with its ambassador to the UN, Ms Nikki Haley, saying: "The time for talk is over."
Influential US Senator Lindsey Graham said on Tuesday that US President Donald Trump had told him he would go to war to prevent Pyongyang from developing a long-range nuclear-armed missile, even if that meant disaster for the peninsula.
"He's got to choose between homeland security and regional stability," Mr Graham said in an interview with NBC.
"If there's going to be a war to stop him, it will be over there. If thousands die, they're going to die over there. They're not going to die here. And he has told me that to my face."
Experts say a months-long conflict on the Korean peninsula, even using only conventional arms, could leave a million dead or injured before US and South Korean forces prevailed.
US Secretary of State Rex Tillerson later insisted the US was not trying to topple the Kim regime. "We are not your enemy. We're not your threat, but you are presenting an unacceptable threat to us and we have to respond," he said.
Mr Jeung Young Tae, director of military studies at the South's Dongyang University, said Pyongyang had crossed a "red line" with its latest missile achievements.
"Whether we want it or not, the risk of unilateral military action by the US cannot be ruled out at this point," Mr Jeung said. The possibility of a military conflict was "bigger than ever before", he added.
Some observers fear an "August crisis".
Later this month, the South and US are due to begin an annual joint army drill long criticised as a rehearsal for invasion by the North, which could respond with a major provocation.