Britain has officially offered Estonia what it calls a nuclear umbrella. Eight other northern European countries received the same offer. The pledge falls under the Joint Expeditionary Force, a British-led defense grouping that brings together partners from the Baltic and Nordic region. For Estonia, which shares a border with Russia, the move comes amid persistent worry about Moscow's intentions. A nuclear umbrella commitment would treat an attack on a partner as grounds for a nuclear-armed response from London. Neither the full terms nor the mechanics of the arrangement were spelled out in the report. The step still ranks among the most explicit security guarantees Britain has put forward for the region so far. Members of the Joint Expeditionary Force train together regularly, and this pledge adds a heavier dimension to that cooperation.