The threat of bombs aboard airplanes has been present since before the war on terror began. Now the U.S. government has issued a new security measure for direct flights to the U.S. due to the fear of a potential new undetectable bomb and the increase in Westerners fighting in the Middle East.

The conflict in Syria and the increased influence exerted by ISIS, along with its success in Iraq, have influenced some Muslims in Western Europe and the U.S. to join them in the so-called holy war. According to CNN, there is a fear that these new jihadists will return home and bring the war to the West.

Along with the threat of jihadists with American or European passports, the U.S. has learned that the Islamist organization al-Qaida in the Arabian Peninsula (AQAP) could be developing new bombs that will be harder to detect in airport security screenings. The AP reports that AQAP has linked with the al-Qaida-associated Nusra Front in Syria and government officials fear that the Western fighters in Syria could return home with the new bombs.

As a result, the Department of Homeland Security implemented new security measures Wednesday. Reuters reports that U.S. officials have placed greater emphasis on inspecting "iPhones made by Apple Inc. and Galaxy phones made by Samsung Electronics Co Ltd." Another threat singled out by the federal government is shoes, since the new bombs could be hidden in soles.

To enforce these new measures, any airline or airport that does not comply with the new rules may have its United States-bound flights banned. However, to maintain security integrity, the Department of Homeland Security has not released many details on how the airlines and airports will implement the security measures.

The government reassures travelers that the new security measures will not significantly lengthen their transit through an airport; however, an official speaking to Reuters added that flying from less sophisticated airports may prove troublesome.