Hamas has seen about half its forces wiped out in eight months of war and is relying on hit-and-run insurgent tactics to frustrate Israel's attempts to take control of Gaza, U.S. and Israeli officials told Reuters. The enclave's ruling group has been reduced to between 9,000 and 12,000 fighters, according to three senior U.S. officials familiar with battlefield developments, down from American estimates of 20,000-25,000 before the conflict. By contrast, Israel says it has lost almost 300...