Four fighter planes land at airbase near Seoul after escorted flyoverFour of the most advanced US fighter jets have flown over South Korea in a clear show of force against North Korea, a day after South Korea’s president warned of the North’s collapse amid a festering standoff over its nuclear and missile ambitions.The F-22 planes, capable of sneaking past radar undetected, landed at Osan airbase near Seoul after the flyover escorted by other US and South Korean fighter jets.