Bomb threats

FILE - In this Dec. 4, 2019 file photo security stand outside the main gate at Joint Base Pearl Harbor-Hickam in Hawaii. A live mortar round was found in a vehicle late Tuesday at a gate to the sprawling Pearl Harbor military base, shutting down the base for hours and leading three people to be taken into custody, military officials said Wednesday, Jan. 15, 2020. A base spokesman said that he doesn't know what the trio planned to do or where they wanted to go. (AP Photo/Caleb Jones, File)

FILE — In this Jan. 19, 2019 file photo the shrine of Iran's revolutionary founder Ayatollah Khomeini is seen, just outside of Tehran, Iran. The ancient and rich cultural landscape of Iran has become a potential U.S. military target as Washington and Tehran stumble toward a possible open conflict. Iran, home to 24 UNESCO World Heritage sites, has in the past reportedly guarded the sprawling tomb complex of the Islamic Republic's founder, Ayatollah Ruhollah Khomeini, with surface-to-air missiles. (AP Photo/Ebrahim Noroozi, File)

FILE - In this photo released by the semi-official Iranian Students News Agency (ISNA), a long-range S-200 missile is fired in a military drill in the port city of Bushehr, on the northern coast of Persian Gulf, Iran, Wednesday, Dec. 29, 2016. The U.S. airstrike that killed a prominent Iranian general in Baghdad raises tensions even higher between Tehran and Washington after months of trading attacks and threats across the wider Middle East. (Amir Kholousi, ISNA via AP)

CORRECTS TO SAY WHAT AUTHORITIES THOUGHT WERE THE REMNANTS OF AN EXPLOSIVE DEVICE TURNED OUT TO BE A NONEXPLOSIVE DEVICE - Marnie Wedgwood hugs her son evacuated from the Rossiter Elementary School in Helena, Mont., Tuesday, Oct. 15, 2019, after authorities found what they thought were the remnants of an improvised explosive device on the school playground. Authorities evacuated the elementary school in Montana's capital city Tuesday after officials found the unknown materials, but they turned out to be a plastic bottle filled with nuts and bolts left in the schoolyard. (Thom Bridge/Independent Record via AP)

FILE - In this Feb. 9, 2015 file photo, an honor guard stands at the entrance before ribbon cutting ceremonies for the new 1st Infantry Division Headquarters at Fort Riley, Kan. Prosecutors say a U.S. Army infantry soldier stationed at Fort Riley shared bomb-making instructions online and also discussed killing activists and bombing a news network. The Justice Department says Monday, Sept. 23, 2019, that private first class Jarrett William Smith was charged with distributing information related to explosives and weapons of mass destruction. (AP Photo/Orlin Wagner File)

An investigator bags a suspicious package as evidence after it was thought to be an explosive device in Manhattan's Chelsea neighborhood Friday, Aug. 16, 2019, in New York. The scare happened about two hours after two abandoned objects that looked like pressure cookers prompted an evacuation of a major transit hub in lower Manhattan. The police bomb squad later determined they were not explosives. (AP Photo/Kevin Hagen).

FILE - This Feb. 27, 2014 file photo shows New York City taxis passing through New York's Times Square. A New York man who talked about wanting to throw a grenade in Times Square has been arrested and is expected to be arraigned Friday on weapons-related charges, law enforcement officials told The Associated Press. (AP Photo/Richard Drew, File)

Secretary of State Mike Pompeo arrives at a classified briefing for members of Congress on Iran, Tuesday, May 21, 2019, on Capitol Hill in Washington. (AP Photo/Patrick Semansky)