U.S. President Donald Trump said on Thursday he will impose tariffs on imports of drones and their components, including from some key U.S. allies, with the Trump administration saying the country was “too reliant” on foreign sources of drones.

A proclamation signed by Trump imposes a 100% ad valorem tariff on drones of a certain size or with certain capabilities that are particularly sensitive for national security purposes, the White House said, adding that a tariff of 25% will be imposed on drones that are smaller in size.

A 15% tariff will be imposed on drones and components from the European Union, Japan, Liechtenstein, South Korea, Switzerland, and Taiwan, and a 10% ad valorem tariff will be imposed on drones from the UK, the White House added.

Trump has made tariffs a central pillar of his foreign and trade policies despite legal setbacks and criticism from some analysts.

Trump said in the proclamation text released by the White House that Commerce Secretary Howard Lutnick had probed the effects of imports of unmanned aircraft systems or drones.

“The Secretary found that import penetration from foreign producers of UAS is substantial and that the United States is too reliant on foreign sources of UAS and UAS components,” Trump said.

Lutnick found that drone and drone components from certain foreign entities “pose security and safety risks” and that the domestic U.S. industry does not produce enough to meet security needs, Trump said.

The tariffs will take effect in 21 days, the White House said.

For components of drones that are not particularly sensitive, the tariffs will take effect 180 days after signing, it said.

For products the Pentagon has approved for an exemption from the Federal Communications Commission’s “Covered List” within 20 days of signing, the tariffs will take effect 180 days after signing, the White House said.