US Homeland Security Secretary John Kelly said Sunday that he was considering banning laptop computers on international flights into and out of the country, amid signs of “a real threat.”

Kelly made his remarks during the Memorial Day weekend, one of the busiest travel periods in the US, and at a time when the bombing at a concert in Manchester, England, has raised concerns that further attacks — possibly involving explosives packed in electronic devices — might be planned.

“There’s a real threat — numerous threats against aviation,” Kelly told the Fox New Sunday program, when asked about the likelihood that a wide-reaching ban on large electronics in airplane cabins could be imposed.

The US homeland security chief said terrorists are “obsessed” with the idea of “knocking down an airplane in flight — particularly a US carrier, if it’s full of mostly US folks.”

A ban could seriously disrupt flights between Europe and the US. Some 3,250 a week are expected this summer between European Union countries and the US, according to aviation industry figures.

If the laptop ban Kelly discussed is put in place, it would greatly expand on a rule he announced March 21, banning electronic devices larger than a smartphone from the cabins of flights from 10 airports in the Middle East and North Africa.

Countries affected by that rule are Turkey, Jordan, Egypt, Saudi Arabia, Kuwait, Qatar, the United Arab Emirates and Morocco.

US President Donald Trump (left) meeting with Russian Foreign Minister Sergey Lavrov in the Oval Office of the White House in Washington, May 10, 2017. (Russian Foreign Ministry via AP)

US President Donald Trump (left) meeting with Russian Foreign Minister Sergey Lavrov in the Oval Office of the White House in Washington, May 10, 2017. (Russian Foreign Ministry via AP)

In March, Britain took similar measures targeting a smaller list of countries: Turkey, Lebanon, Jordan, Egypt, Tunisia and Saudi Arabia.

At the time, US officials insisted the ban wasn’t based on any specific threat but on longstanding concerns about extremists targeting jetliners. But earlier this month, US President Donald Trump passed on classified intelligence to senior Russian officials about an Islamic State plan to blow up a passenger plane headed for the US by hiding a bomb in a laptop.

Later reports said an Israeli intelligence asset embedded in the terrorist group had provided the tip-off about the planned IS attack, and that Trump’s information-sharing possibly put the spy’s life at risk.

In Europe last week, during Trump’s nine-day foreign trip, Kelly met with European Commission officials in Brussels to discuss a possible laptop ban in airplane cabins.