WASHINGTON — President Obama plans to convene a special session next week on global efforts to defeat the Islamic State as part of a major nuclear summit that he is leading in Washington, senior administration officials said.
Obama’s decision to add a session on the Islamic State to a summit that is focused on securing nuclear materials is a sign of the deep concern in the White House and worldwide after attacks in Paris, San Bernardino, Calif., and Brussels.
Those strikes have exposed major shortcomings in the police and intelligence forces of many of America’s closest allies and raised new concerns about the nearly 6,000 ‘‘foreign fighters’’ from the West who are believed to have traveled to Iraq and Syria.
The White House said it will also be holding additional counterterrorism-focused meetings with world leaders.
Belgian authorities stripped the security badges of several employees at one of two nuclear power plants in Belgium on Friday, after clearing out some personnel at both sites just hours after the attacks in Brussels this week.
The steps contributed to fresh alarm that the Islamic State is seeking to attack or sabotage nuclear facilities or obtain radioactive material in a country with an already troubled history of security lapses at its atomic sites and weak counterterrorist agencies.
Next week’s Nuclear Security Summit is also expected to focus on the Islamic State’s ambitions to obtain a weapon of mass destruction. There is little indication that the Islamic State has access to the radioactive material needed to make a ‘‘dirty bomb.’’
Syria and Iraq are free of highly enriched uranium and plutonium, officials said. But the Islamic State has used crude chemical weapons, employing mustard gas and chlorine, in both Iraq and Syria. The terrorist group’s control over large areas of Iraq and Syria could give it access to experts and facilities that, over time, could allow it to develop more sophisticated and deadly chemical weapons.
Thes summit, which will bring as many as 50 world leaders to Washington, offers a rare forum for Obama to talk with his counterparts around the globe about the threat posed by the terrorist group.
Planning for an extra session began in January after the Paris and San Bernardino attacks, senior administration officials said.
‘‘This has been something we’ve been working on for quite a while,’’ one of the officials said. Tuesday’s attacks in Brussels only added to the urgency of the effort.
All 50 nations represented at the nuclear summit have been sources of fighters for the Islamic State in Iraq, in Syria, or elsewhere in the Middle East, the administration official said.
The nuclear summit — the fourth led by Obama since 2010 — has focused in previous years on securing vulnerable nuclear materials, breaking up black markets and intercepting illicitly trafficked materials. In addition to those topics, Obama and the world leaders will discuss ways to slow the flow of foreign fighters and money to the Islamic State in Iraq and Syria.
Breakdowns in intelligence-sharing between nations are also likely to be a major subject of discussion. Two of the siblings who blew themselves up in Tuesday’s attacks had entered Turkey illegally with the goal of eventually going to fight in Syria.
The elder brother, Ibrahim el-Bakraoui, 29, was stopped by Turkish authorities and sent back to Europe, but Belgian officials said they didn’t track him as a potential terrorist threat. The younger brother, Khalid el-Bakraoui, 27, was also monitored by Turkey, but it’s not clear that Belgian authorities were aware of his movements.
After the Paris attacks, the Obama administration sent ‘‘foreign fighters surge teams’’ to Belgium and another European country to help local authorities improve intelligence-sharing among intelligence and law enforcement officials as well as across international borders.
The teams also brought new technology to aid in the tracking of those fighters and organizational lessons that the United States learned in the nearly 15 years following the 9/11 attacks.
In Belgium, the foreign fighter teams’ efforts weren’t enough to stop Tuesday’s attacks. Still, a senior administration official said there is a ‘‘huge appetite’’ among European allies for help with the threat posed by foreign fighters. The summit could provide an opening to expand the teams and send them to other countries that are struggling to deal with the problem posed by foreign fighters.