The Pentagon wants to expand the military’s ability to battle al-Qaida-linked militants in Somalia, potentially putting U.S. forces closer to the fight against a stubborn extremist group that has plotted attacks against America, senior U.S. officials said. The recommendations sent to the White House would allow U.S special operations forces to increase assistance to the Somali National Army in the struggle against al-Shabab militants in the fragile Horn of Africa nation, the officials said.