KUALA LUMPUR, Malaysia — The poison used to kill the estranged half- brother of North Korea’s leader at a crowded air terminal in Malaysia last week was the banned chemical weapon VX nerve agent, police said today.

The revelation that VX nerve agent, deadly even in minute amounts, was used in the Feb. 13 attack boosted speculation that Pyongyang dispatched a hit squad to kill Kim Jong Nam, the outcast older sibling of North Korea’s ruler.

The case also raised questions about public safety, although there was no sign that any bystanders had fallen ill. Police said one of the alleged attackers had been vomiting in the hours after the attack, but there were no reports that anyone else had been sickened.

Police had gone more than a week saying the airport was safe, even though it had not been decontaminated after a mysterious and deadly poisoning. After the announcement that VX was to blame, The Associated Press asked Malaysia’s Inspector-General of Police Khalid Abu Bakar in a text message whether decontamination would take place. He responded, “We are doing it now.”

He later said police were arranging for the atomic energy agency to decontaminate the airport and “sweep all locations which we knew that the suspects went to.”

Asked if people should avoid the airport because of fears of contamination, Khalid said, “No. No. No. But I don’t know. I am not the expert.”

Director-General Hamrah Mohamad Ali of the Atomic Energy Licensing Board later told The Associated Press in a text message that although his office received a police request for technical assistance, VX doesn’t come under his jurisdiction because it’s not radioactive.

The airport operator said in a statement issued today that the KLIA2 terminal where Kim was attacked is safe.