Major Japanese carriers will start randomly checking passengers' electronic devices for explosives before they board aircraft, responding to a U.S. request to enhance aviation security to counter terrorism, airport sources said Friday.

The new measure will be taken from Tuesday, likely affecting Tokyo's Haneda airport and Narita airport near the capital as well as five other airports in the country that have direct flights to the United States. The implementation could cause flight delays as many passengers may be unaware of the new policy.

The random screening will be conducted on electronic devices passengers have as carry-on items, such as personal computers, tablet computers, electronic book readers and cameras, the sources said. Cell phones and smartphones are exempt from the checks.

The screening will use special checking devices as the U.S. government has called for the use of so-called Explosive Trace Detectors, which can detect traces of explosives by wiping on electronic devices.

The checks will likely be conducted at departure gates, rather than security check areas, as the United States is calling for passengers who are already screened not to be allowed to mingle with those who are boarding other flights.

According to Japan's Ministry of Land, Infrastructure, Transport and Tourism, the five other airports that have direct flights to the United States are New Chitose, Sendai, Chubu, Kansai and Fukuoka.

In late June, the United States unveiled its enhanced security measures that will affect U.S.-bound commercial flights through expanded screening of passengers and their carry-on electronic devices at departing airports.

The U.S. Department of Homeland Security has expressed concerns that terrorists are improving their methods to plant explosives in electronic devices. It claims an explosives-laden laptop was used in a terrorism case in Somalia in February 2016.