Afghanistan: On a Day Devoted to Past Events, Focus on New Terror Link --- WASHINGTON — The morning after committing the nation to an expanded military campaign against Islamist terrorism, President Obama honored the victims of the Sept. 11, 2001, attacks as the White House argued that he had the right to wage his new fight under the same legal authority he used to hunt down Osama bin Laden and Al Qaeda. -- On a day suffused with memories of four hijacked planes and the war they ignited, the president’s new mission seemed less a break from the past than the continuation of a long national struggle. -- The Islamic State in Iraq and Syria, the administration said, was formerly the Iraqi affiliate of Al Qaeda, and has maintained ties with Al Qaeda even after its very public falling-out with Qaeda leaders. It uses brutal tactics that are out of the Qaeda playbook, and is viewed, even by some members of Al Qaeda, as the legitimate heir to Bin Laden’s legacy. -- The argument, laid out Thursday by Josh Earnest, the White House press secretary, could spare the president’s lawyers from having to negotiate a new legal authorization from Congress, should Mr. Obama decide to ask lawmakers to approve a prolonged military campaign. -- But it ties his efforts against ISIS more firmly to the war on terrorism waged by him and his predecessor George W. Bush in the decade after the 2001 attacks, even though Mr. Obama insists they are different. In his prime-time speech to the nation on Wednesday, Mr. Obama drew a distinction between the ISIS campaign and the wars in Iraq and Afghanistan, saying it was a new kind of counterterrorism operation that would rely on bolstering local troops rather than deploying American ones. --- On Thursday, Mr. Obama paid tribute to the service members and civilians killed at the Pentagon. Speaking before a giant American flag draped over the part of the Pentagon wall where one of the hijacked planes crashed, Mr. Obama said, “Thirteen years after small and hateful minds conspired to break us, America stands tall and America stands proud.” -- The president hailed the “9/11 generation” of soldiers who have served in the years since the 2001 attacks, noting that “three months from now, our combat mission in Afghanistan will come to an end.” -- Mr. Obama made no mention of ISIS, speaking only of challenges facing the country. But his description of a nation coping with the threat of terrorism seemed entirely relevant today. “We carry on because as Americans, we don’t give in to fear — ever,” he said.