Ukrainian President has implored Western allies to provide his country with military aid as Russia continues its unprovoked invasion.

"We need you right now," Zelensky in one of his latest pleas for assistance before a friendly government.

The U.S. and other NATO member nations have Zelensky's requests, while stopping short of certain measures they say could risk an escalation in the war.

WEAPONS ASSISTANCE

The military aid provided to Ukraine so far includes weapons that range from portable drones to complex, long-range missile systems.

Switchblade drones. Small, portable, so-called kamikaze drones that carry warheads and detonate on impact. The smallest model can hit a target up to six miles away, according to the company that produces the drones, AeroVironment. It's unclear which size model the U.S. will send to Ukraine.

Stinger anti-aircraft missiles. These heat-seeking, anti-aircraft missiles have a range of about five miles and 11,000 feet. Critically, Stinger missiles can distinguish between enemy and friendly aircraft.

Javelin anti-tank weapons. This guided missile system can be shoulder-fired by a single solider and has a range of up to 8,200 feet.

AT-4 anti-armor systems. These Swedish anti-armor weapons are "lightweight, single-shot and fully disposable," according to the company that produces them, .

Patriot air defence missile system. The U.S. also delivered two missile defence systems to Poland this month intended to deter Russia and boost Poland's security amid Western concerns that the Ukraine conflict could spill into NATO-aligned nations.

The Patriot air defence missile system -- Patriot stands for "" -- is designed to counter and destroy incoming short-range ballistic missiles, advanced aircraft and cruise missiles.

The battery includes missiles and launching stations, a radar set that detects and tracks targets, and an engagement control station, according to the Missile Defence Advocacy Alliance.

OTHER ACTIONS

Beyond military aid to Ukraine, the U.S. and its NATO allies have issued a slew of sanctions against Russia.

Putin. The United States, European Union, United Kingdom and Canada have announced they would introduce sanctions targeting Russian President Vladimir Putin and Russian Foreign Minister Sergey Lavrov.

SWIFT. The U.S., EU, U.K. and Canada have banned certain Russian banks from SWIFT, the high-security network that facilitates payments among 11,000 financial institutions in 200 countries.

'Most favoured nation' status. The U.S. House of Representatives has passed a bill to with Russia. The final vote was 424-8 with strong bipartisan support for the legislation, which next heads to the Senate.

Energy and oil. EU officials would slash imports of Russian natural gas by two-thirds this year, and the EU announced a plan to achieve energy independence from Moscow "well before 2030." That would separate Europe from its single biggest energy supplier.

Separately, announced a , natural gas and coal imports to the United States. And the UK government said Tuesday it would phase out Russian oil imports by the end of 2022 and explore ways of ending natural gas imports as well.

Nord Stream 2 gas pipeline. Germany has halted certification of the Nord Stream 2 gas pipeline following Moscow's actions.

UNFULFILLED URKAINIAN REQUESTS

As Russia's deadly invasion has continued, Zelensky has requested some actions that Western allies fear would put them in direct conflict with the Kremlin and escalate the war.

No-fly zone. Zelensky has repeatedly called on Ukraine's allies to establish aover the country. A no-fly zone is an area where certain aircraft cannot fly for any number of reasons. In the context of a conflict such as the one in Ukraine, it would probably mean a zone in which Russian planes were not allowed to fly, to prevent them from carrying out airstrikes against Ukraine.

The problem with military no-fly zones is that they have to be enforced by a military power. If a Russian aircraft flew into a NATO no-fly zone, then NATO forces would have to take action against that aircraft. Those measures could include shooting the plane from the sky. That would, in Russia's eyes, be an act of war by NATO and would likely escalate the conflict.

S-300 missile defence systems. This surface-to-air missile system can strike targets that are both higher in altitude and farther away than Stinger missiles are designed for.

Slovakia has to provide Ukraine with a key Soviet-era air defence system to help defend against Russian airstrikes, according to three sources familiar with the matter. But the U.S. and NATO are still grappling with how to backfill that country's own defensive capabilities, and the transfer is not yet assured.

MiG fighter jets. Earlier this month, the U.S. dismissed to transfer its MiG-29 fighter jets to the United States for delivery to Ukraine.

Pentagon press secretary John Kirby said in a statement that the U.S. did not believe Poland's proposal was "tenable" and that it was too risky.

"The prospect of fighter jets 'at the disposal of the Government of the United States of America' departing from a U.S./NATO base in Germany to fly into airspace that is contested with Russia over Ukraine raises serious concerns for the entire NATO alliance," Kirby said.