The United States has expressed concern over Russia’s transfer of nuclear weapons to Belarus and called Iran’s new missile a serious threat.

“The transfer of nuclear munitions has begun,” Belarusian leader Alexander Lukashenko told reporters Thursday during a visit to Moscow to meet with President Vladimir Putin.

In Washington, White House Press Secretary Karine Jean-Pierre called Russia’s move “irresponsible and provocative choices.”

As to the Kheibar missile that Iran test-fired this week, State Department spokesperson Matthew Miller told reporters in Washington that “Iran’s development, and proliferation of, ballistic missiles poses a serious threat to regional and international security and remains a significant non-proliferation challenge.”

The Kheibar has a range of 2,000 kilometers and be able to carry warheads weighing over one ton, Iran’s defense ministry said.

“An Iran with a nuclear weapon would likely act even more provocatively, and that’s why we are so committed to preventing Iran from acquiring nuclear weapons,” Miller said.