Secretary-General Jens Stoltenberg said today that "no decision has been taken. The discussion is going on."
He told reporters in Brussels that it "is absolutely out of the question for NATO to go into combat operations."
US President Donald Trump is expected to pressure NATO to do more to fight extremists in Syria, Iraq and Afghanistan when he meets his allied counterparts in Brussels on May 25.
NATO supports the coalition with training and aerial surveillance. But members do not want NATO fighting Islamic State, even though all are also individual members of the anti-IS coalition.