“Nato signed an act in 1997 agreeing that it would not establish permanent bases in ex-Soviet states such as the Baltics,” says Elisabeth Braw, director of Rusi’s modern deterrence project. Though details of the plans are vague, Braw suggests that the US could get around this by leaving the troops on “permanent rotation”. But the message would be clear. “You have to weigh the benefits against the costs,” she says. “While the Baltics are strategically important, creating military bases there would aggravate Russia.”