The UK has followed the U.S. in enforcing stricter security measures at its airports after Washington warned European authorities of a “credible” terrorist threat.

While neither country provided details on what they would change to strengthen current security measures, they clarified that these changes will not bring any major disruptions. The U.S. Department of Homeland Security had released a statement Wednesday stating that there are “necessary” steps that authorities need to take and that it has conveyed the message of the threat to its counterparts around the world.

“We have taken the decision to step up some of our aviation security measures. For obvious reasons we will not be commenting in detail on those changes. The majority of passengers should not experience significant disruption. There will be no change to the threat level, which remains at substantial,” the British Department of Transport said, in a statement Wednesday.

American authorities reportedly uncovered a plot by factions of the militant group al-Qaida to make bombs that could be smuggled onto planes, and issued a warning to countries in the region to enhance security measures at airports. Bomb experts from the Yemen-based al-Qaida and its Nusra front in Syria are reportedly working together on making explosives that could pass undetected at airport security screenings.

“I have directed TSA (Transportation Security Administration) to implement enhanced security measures in the coming days at certain overseas airports with direct flights to the United States. We will work to ensure these necessary steps pose as few disruptions to travelers as possible. We are sharing recent and relevant information with our foreign allies and are consulting the aviation industry,” Jeh Charles Johnson, Homeland Security secretary, said, in a statement released on Wednesday.

According to a Reuters report, which cited government officials, authorities are worried militants might try to bomb planes bound for the U.S. and Europe with the help of people who hold Western passports and are sympathetic to the group's cause.

Heathrow is one of the busiest airports in the world and serves nearly 200,000 passengers a day, according to Reuters.