For a hypothetical conflict in the Pacific, the common frame is of forward, proactive U.S. forces beset by Chinese A2/AD systems intent on denying U.S. ships and aircraft use of the waters and airspace inside the first island chain, the string of islands stretching from Japan south to the Philippines that encircles China from the sea, and even threatening forces as far away as the second island chain, like U.S. bases on Guam. The idea of a U.S. A2/AD umbrella is rarely considered, but the U.S. Army is working to build a future capability to achieve just that via its ‘Multi-Domain Battle’ concept.