The US Senate has approved a $61 billion military aid package for Ukraine, and it is now on President Joe Biden's desk to become law. What kind of weaponry might Ukraine acquire, and how would that affect their efforts to halt Russian aggression?

Three types of weapons are the most urgently needed by Ukraine: artillery rounds, mid- to long-range missiles, and air defence systems. This is where US assistance in these places could be directed.

Air defence

Repelling the Russian threat from the skies is vital for the protection of cities and critical infrastructure such as energy plants.

Last week Ukrainian President Volodymyr Zelensky said his country had been attacked by almost 1,200 Russian missiles, more than 1,500 drones and 8,500 guided bombs this year alone.

Ukraine has a variety of western-supplied systems ranging from shoulder-launched Stinger short range missiles all the way up to the advanced - and extremely expensive - Patriot system. Zelensky said at least seven more Patriots, or their equivalent, were needed.

Russia's cruise and ballistic missiles - including converted S-300 and S-400 surface to air missiles - along with hundreds of Iranian-made Shahed-136 drones - are difficult to counter because of the sheer volumes launched.

A classic tactic to overwhelm air defences is to swamp them with targets, thereby occupying their acquisition and tracking radar systems and depleting missile stocks.

Mid to long-range missiles

But the war on the ground is vital. Since October, Ukraine has lost nearly 583 square kilometres (225 square miles) of its eastern territory to Russian forces, largely because of a lack of artillery.

High Mobility Artillery Rocket Systems (HIMARS) have played a crucial role for Ukraine, by delivering guided munitions from a mobile platform.

Arrive at location, set-up, fire and quickly move on before Russian forces can locate and attack the launcher. Expect more HIMARS capability in Ukraine, and perhaps a commitment for more tanks and Bradley infantry fighting vehicles.