"I'm trying to make sense of it and wonder what was going through the mind of the person when they were carrying this out", Plotkin said.
"As Jews and Israelis, we are often persecuted", Eliezer said. "We urge all institutions to remain vigilant in the wake of this high-profile case and global media coverage".
Thursday's arrest is the second in response to the threats.
He was arrested on Thursday morning at home in Ashkelon town in Israel.
Nelson and Republican U.S. Sen. Marco Rubio wrote a letter earlier in March to federal officials seeking swift action on the threats.
The Anti-Defamation League, which monitors anti-Semitism in the United States, welcomed the arrest but called on Jewish communities to remain vigilant.
Concerns about anti-Semitism have been at the forefront during these threats. Each wave consisted of threats made by telephone, with multiple states and centers targeted at once. Some Jewish institutions in Missouri had also received bomb threats.
"We're not 100 per cent sure", she said.
Police said the suspect was responsible for a bomb threat against Delta Airlines flight 468 in January 2015 at New York's John F. Kennedy airport.
The unnamed American-Israeli Jewish teenager, accused of making dozens of anti-Semitic bomb threats in the United States and elsewhere, is escorted by guards as he leaves the Israeli Justice court in Rishon Lezion.
While they "did not say anything conclusive, I was led to believe there was a direct connection" to threats against Baltimore-area centers, he said.
The man is also suspected of placing threatening phone calls to Australia, New Zealand and within Israel. Israeli police say he used advanced technology to cover up the origin of his calls and communications.
The lawyer said that a peculiarity of the American-Israeli treaty is that Israeli nationals found guilty in the USA can serve their prison sentences either in the states or the Middle East, meaning that the authorities who arrested the suspect on Thursday could wait until he is sent back to their country before putting him on trial.
"He didn't use regular phone lines". But Jewish leaders said an apparent rise in anti-Semitism beyond the specific JCC threats, including desecration of Jewish cemeteries and painting of swastikas in schools, has helped bolster the case that enhanced security is needed. The threat allegedly led to an emergency landing.
"We are relieved that no one has been hurt, and that all of the bomb threats around the country were determined to be hoaxes", Gray said. Trump condemned the attacks during his speech to a joint session of Congress Feb. 28.
Jordan Shenker, head of the Kaplen Jewish Community Center which was affected by the threats, said he is confident that the threats will be over and that he can breathe again.