Iran has deployed subject experts successful Russian-occupied Crimea to assistance motorboat drone attacks connected Ukraine, the White House says.
The Iranians are trainers and tech enactment workers, a US spokesperson said.
The Ukrainian capital, Kyiv, was struck by alleged "kamikaze" drones connected Monday, deployed by Russia but believed to beryllium Iranian-made.
The UK has announced sanctions connected Iranian businesses and individuals liable for supplying the drones.
"We measure that Iranian subject unit were connected the crushed successful Crimea and assisted Russia successful these operations," White House nationalist information spokesperson John Kirby told reporters.
A "relatively small" fig of Iranians are providing method enactment and Russians are piloting the drones successful Ukraine, helium said.
"Tehran is present straight engaged connected the ground, and done the proviso of weapons that are impacting civilians and civilian infrastructure successful Ukraine," Mr Kirby said.
The US volition "pursue each means" to "expose, deter and face Iran's proviso of these munitions against the Ukrainian people", helium added.
Ukraine identified the drones - oregon unmanned aerial vehicles (UAVs) - utilized connected Monday arsenic Iranian Shahed-136 weapons.
They are known arsenic "kamikaze" drones due to the fact that they are destroyed successful the onslaught - named aft the Japanese combatant pilots who flew termination missions successful World War Two.
Russia has utilized the drones and missiles to deed captious infrastructure astir Ukraine successful caller days, destroying astir a 3rd of the country's powerfulness stations since Monday past week.
The UK has announced sanctions connected 3 Iranian generals and an arms steadfast implicit Russia's usage of Iranian drones to onslaught Ukraine.
UK Foreign Secretary James Cleverly accused those listed of "warmongering" and profiting disconnected Moscow's "abhorrent" attacks.
Among those targeted is the main of unit of Iran's equipped forces, Major General Mohammad Hossein Bagheri, arsenic good arsenic Shahed Aviation Industries, a drone manufacturer.
Ukraine's President Volodymyr Zelensky has accused Moscow of attempting to unit radical to fly their homes for EU countries by attacking powerfulness plants.
"Russian panic against our vigor facilities is aimed astatine creating arsenic galore problems with energy and vigor arsenic imaginable for Ukraine this autumn and winter, truthful that much Ukrainians spell to European countries," helium said successful remarks to an EU acme connected Thursday.