WASHINGTON — Al Qaeda’s top leadership in Pakistan, badly weakened after a decade of C.I.A. drone strikes, has decided that the terror group’s future lies in Syria and has secretly dispatched more than a dozen of its most seasoned veterans there, according to senior American and European intelligence and counterterrorism officials.

The movement of the senior Qaeda jihadists reflects Syria’s growing importance to the terrorist organization and most likely foreshadows an escalation of the group’s bloody rivalry with the Islamic State, Western officials say.

The operatives have been told to start the process of creating an alternate headquarters in Syria and lay the groundwork for possibly establishing an emirate through Al Qaeda’s Syrian affiliate, the Nusra Front, to compete with the Islamic State, from which Nusra broke in 2013. This would be a significant shift for Al Qaeda and its affiliate, which have resisted creating an emirate, or formal sovereign state, until they deem conditions on the ground are ready. Such an entity could also pose a heightened terrorist threat to the United States and Europe.

Qaeda operatives have moved in and out of Syria for years. Ayman al-Zawahri, the group’s supreme leader in Pakistan, dispatched senior jihadists to bolster the Nusra Front in 2013. A year later, Mr. Zawahri sent to Syria a shadowy Qaeda cell called Khorasan that American officials say has been plotting attacks against the West.