WASHINGTON — The recent attacks in Paris and Beirut and the downing of a Russian airliner in Egypt were the first results of a centrally planned terrorism campaign by a wing of the Islamic State leadership that oversees “external” targets, according to US and European intelligence officials.

The Islamic State’s overseas operations planning cell offers strategic guidance, training and funding for actions aimed at inflicting the maximum possible civilian casualties, but leaves the task of picking the time, place and manner of the attacks largely to trusted operatives on the ground, the officials said.

Carrying out attacks far from the Islamic State’s base in Iraq and Syria represents an evolution of the group’s previous model of exhorting followers to take up arms wherever they live — but without significant help from the group. And it upends the view held by the United States and its allies of the Islamic State as a regional threat, with a new assessment that the group poses a whole new sets of risks.

“Once the Islamic State possessed territory that provided them sanctuary and allowed them to act with impunity, they like other jihadist groups inevitably turned to external attacks,” said Dr William Wechsler, a senior fellow at the Center for American Progress and until last January a top counterterrorism official at the Pentagon.

One possible motivation of the change in strategy by the Islamic State, also called ISIS or ISIL, is to seize leadership of the global jihad from al-Qaida - from which the Islamic State broke away in 2013. The attack on the Radisson Blu hotel in Mali on Friday was probably carried out by two al-Qaeda-linked groups, suggesting, as one senior European counterterrorism official put it: “The race is on between ISIS and al-Qaida to see who can attack the West the best.”

US and European intelligence officials said they based their new assessment of the external operations structure on intercepted communications, the Islamic State’s own propaganda, and other intelligence.

Investigators are still piecing together details of how the Paris plotters communicated, but two Western counterterrorism officials revealed that there were electronic communications between Islamic State leaders in Syria and Abdelhamid Abaaoud, the man suspected to be the architect of the assault, in the weeks before the attacks.

Similar evidence analysed after the bombings in Beirut, the Lebanese capital, suggest that those strikes were directed from Syria and conducted by operatives on the ground. The downing of the Russian airliner followed a larger Islamic State goal to strike Russian interests but was probably carried out autonomously by the group’s affiliate in Egypt, officials said.

According to US and European officials, the man overseeing the attacks outside Iraq and Syria is Abu Muhammad al-Adnani, a 38-year-old Syrian who is the official spokesman for the Islamic State and one of the most trusted lieutenants of Abu Bakr al-Baghdadi, the group’s supreme leader. But it is in his dual role as head of external operations that Adnani has drawn intensified scrutiny from Western officials.

Adnani is best known for a 42-minute audio statement issued on social media in September 2014 in which he called on individual Muslims living in the West to kill civilians in their countries by any means necessary, and to do so without waiting for further instructions from the terrorist group’s leaders.

“If you can, kill a disbelieving American or European — especially the spiteful and filthy French — or an Australian, or a Canadian,” he said. “Then rely upon Allah, and kill him in any manner or way, however it may be. Do not ask for anyone’s advice.”

As a result, Adnani now has a US$5 million (S$7.1 million) bounty on his head, offered by the United States, and is on the kill list for the US-led air campaign in Iraq and Syria. “Adnani has been a key figure in external planning since ISIS rose to prominence over a year ago,” said Matthew G Olsen, a former director of the National Counterterrorism Center.

French intelligence officials believe that Abaaoud, who was killed in a shootout with the police in Paris last week, worked under Adnani in Syria, impressing his boss by recruiting French-speaking jihadists.

According to activists from Aleppo province in Syria, Abaaoud spent time in Azaz, near the Turkish border, in early 2014. Azaz at the time was a kind of foreign jihadist boomtown, full of enthusiastic new arrivals. According to the activists, Abaaoud served as the emir, or leader, of foreign fighters there until the Islamic State was pushed out of the area and moved to the east, including to Deir al-Zour.

Abaaoud kept a low profile among civilians there, said Omar Abu Layla, an anti-government activist from Deir al-Zour, but gained a reputation in skirmishes against groups calling themselves the Free Syrian Army that oppose both the Islamic State and the Syrian president, Bashar Assad. Abaaoud’s enemies called him “the mongoose,” for his ability to operate discreetly, quickly and quietly, establishing his presence and power.

Western officials say the Belgian-born Abaaoud was eventually assigned a bigger role: to organise attack missions in Europe. There, he drew upon a vast network of radicals and extremists long before the Paris strikes.

The French interior minister, Bernard Cazeneuve, said at a news briefing on Thursday that Abaaoud, in addition to playing an important role in the Paris attacks, had his hand in at least four of the six plots French authorities had broken up this year.

A Belgian counterintelligence official said the Islamic State operated cells like Abaaoud’s based on language ties, such as a francophone group. The cells are also grouped to facilitate the planning of attacks on areas they are most familiar with. For instance, French plotters who knew which landmarks to strike worked with Belgians who knew they could organize plots and buy weapons, all under the radar, in Belgium.

These cells worked in what the official called a “bamboo” structure * most militant groups have cells intended to operate separately and in parallel to ensure that if one member is killed or a plot is aborted, the demise would not affect other plots.

Mr John O Brennan, the director of the Central Intelligence Agency, said last week that the Paris attacks, as well as the downing of the Russian jet over the Sinai Peninsula and the suicide bombings in Beirut, all bore the “hallmarks” of the Islamic State.

The timing of the Russian charter jet crash with the attacks in Beirut and Paris is the most visible indication yet that the Sinai Province group may be taking broad guidance from the Islamic State, counterterrorism officials said.

“Europe has been taken by surprise by Daesh’s ability, determination and motivation to carry out such spectacular, coordinated and violent attacks outside the territory it holds instead of focusing on consolidating the caliphate,” said another senior European counterterrorism official, using an Arabic acronym for the group.

It should not have been. Abu Musab al-Zarqawi, the leader of al-Qaida in Iraq, the forerunner to the Islamic State, was always interested in external attacks, notably the bombing of three hotels in Amman, Jordan, in 2005 that killed 60 people, according to U.S. and European intelligence officials. NEW YORK TIMES