According to a Russian state media report related by Turkey’s Hurriyet Daily News, the United States is planning to send next-generation B61 nuclear gravity bombs to NATO bases in several European countries, including Turkey.

The bomb is said to be compatible with F-35 joint strike fighters, which Turkey is also due to receive amid some controversy.

Hurriyet describes the B61 nuclear bomb and Russia’s sour reaction to the prospect of NATO bases receiving them:

The U.S. Department of Energy’s National Nuclear Security Administration (DOE/NNSA) and the U.S. Air Force completed two non-nuclear system qualification flight tests of the B61-12 gravity bomb on June 9 at Tonopah Test Range in Nevada, according to a June 29 statement by DOE/NNSA.

The test, which was reportedly the first of its kind, was aimed at extending the B61 bomb’s service life by adapting it to next generation aircraft, including B-2A Spirit Bomber.

“The B61-12 LEP will consolidate and replace the existing B61 bomb variants in the [U.S.] nuclear stockpile. The first production unit is on schedule for completion in fiscal year 2020,” the statement said.

Russia’s state-run RIA news agency claimed on July 2 that the nuclear bomb will also be adapted to the F-35 aircrafts.

“The United States continues to invest in weapons of mass destruction. The NATO bases in Turkey, Germany, and Italy will receive the new bombs in 2020,” Russian nuclear expert Alexandr Jilin was quoted as saying by the agency.

Military.com reports the B61 did indeed pass two non-nuclear system qualification tests on June 9. According to U.S. Air Force officials, the bomb program has been subjected to 26 engineering, development, and guided flight tests, and is doing “extremely well.”

Military.com also confirmed that the F-35 is meant to be capable of carrying B61 bombs, and has conducted flight tests with inert copies of the weapon.

Russian military planners are reportedly worried about the B61 because they have no comparable small-yield precision nuclear weapon, relying instead on cruise missiles that can only be launched from larger strategic aircraft. European defense planners have expressed great interest in the new generation of American nuclear gravity bombs because they would be able to turn older fighter-bombers into tactical nuclear strike aircraft.