The submarines, nicknamed Boomers, gained the silent service description because they are designed to glide undetected, and their port calls have seldom been disclosed — much less trumpeted — by their usually taciturn commanders. © Photographer: David Nagle/US Navy/Getty Images Navy Tests Converted Guided Missile SubThe US has occasionally showcased its submarines in the past, but the pace picked up in the last year with publicized port visits by nuclear-armed Ohio-class submarines as well as Los Angeles-class subs carrying conventional Tomahawk cruise missiles. “Those concerns are true, but US submarines are still the quietest and most sophisticated in the world,” he said. Increased visibility could have its downside, especially the South Korea visit, said Brent Sadler, the Heritage Foundation’s senior research fellow for naval warfare and a Navy veteran with numerous submarine tours. The strategic messaging of support for South Korea “would be minimal” for the US “to take some significant risks to send such a boat that far forward,” he said.