WASHINGTON The US Department of Defense announced an additional US$2.1 billion in security assistance for Ukraine on Friday, including air defence and ammunition capabilities, amid signs that Kyiv had begun its long-awaited counteroffensive against Russia.

The package includes additional munitions for Patriot air defence systems, Raytheon HAWK air defence systems and missiles, 105mm and 203mm artillery rounds, small AeroVironment drones that can be launched by hand, laser-guided rocket system munitions and support for training and maintenance, the Defense Department said.

Ukraine Security Assistance Initiative (USAI) funds will be used to purchase the weapons, allowing President Joe Biden's administration to buy weapons from industry, rather than pull them from US stocks.

Delivery of the weapons and systems depends on their availability and production timeline.

The announcement came as Ukraine's long-anticipated counterattack seemed to be under way. Russia reported heavy fighting along the front in southern Ukraine, and bloggers described the first sightings of German and US tanks and armoured vehicles.

The Pentagon has provided more than US$7 billion in security assistance for Ukraine under the USAI, in five separate tranches. In the fiscal year that ended Sept 30, 2022, Washington put US$6.3 billion worth of USAI funds to work buying for Ukraine's defence.

Biden said at a press conference with British Prime Minister Sunak on Thursday he was confident Washington could have the necessary funding to support Ukraine "for as long as it takes," despite skepticism from a few Republicans in Congress.

In a statement, the Department of Defense said the latest announcement "illustrates the continued commitment to both Ukraine’s critical near-term capabilities as well as the enduring capacity of Ukraine’s Armed Forces to defend its territory and deter Russian aggression over the long term."

In total, the United States has committed up to US$40 billion in security assistance to Ukraine since Russia’s invasion on Feb 24, 2022.

  - Reuters