Iran has given ballistic missiles to its Shiite proxies in Iraq, Reuters reports, in a move that will escalate tensions between Iran and the U.S. even further. Iran is also reportedly developing the capacity to build more missiles inside Iraq to strengthen its ability to deter attacks. The country’s more aggressive missile policy is likely to ring alarm bells in Washington—relations between the two countries have become increasingly antagonistic after Donald Trump’s decision to pull out of a 2015 nuclear deal with Iran and world powers. Unnamed Iranian and Iraqi intelligence sources said Iran has been transferring short-range ballistic missiles to allies in Iraq over the last few months. “The logic was to have a backup plan if Iran was attacked,” one senior Iranian official said. “The number of missiles is not high, just a couple of dozen, but it can be increased if necessary.” Iran has previously said its ballistic missile activities are purely defensive—its government didn’t respond when asked about the latest moves.