Amid heightened tensions in the Middle East after Iran’s attack on Israel, the U.S. State Department said the United States is "incredibly concerned" about the long-suspected military cooperation between North Korea and Iran.

Department spokesperson Matthew Miller made the remarks on Tuesday during a press briefing when asked if the U.S. has concerns about Iran working with Pyongyang on nuclear and ballistic missile programs.

North Korea and Iran established diplomatic ties in 1973 and have since maintained friendly and cooperative relations amid speculations and concerns about their suspected cooperation in nuclear and missile technology. 

In a separate briefing on Tuesday, Pat Ryder, the spokesperson for the U.S. Defense Department, said that the U.S. cannot speculate about the possibility that North Korean weapons were used in Iran’s attack on Israel, but the U.S. takes threats posed by the North and Iran "very seriously." 

Ryder then reaffirmed that similar to the U.S.’ defense of Israel, its alliances with South Korea and Japan are also ironclad, vowing to stand beside them to work towards security and stability in the Indo-Pacific region.