Javelin Missiles: At least 280 Russian Tanks have been Destroyed with the American Javelin missile.

300 Shots Fired, 280 Russian Tanks Gone: US Missiles In Ukrainian Hands
Javelin missiles in Ukraine: At least 280 Russian armoured vehicles have been destroyed with the American Javelin missile, out of 300 shots fired, according to a report
The Ukrainian military fighting the much larger Russian invasion force has been able to kill hundreds of Russian tanks and armoured vehicles using a hand-held anti-tank missile supplied by the US, according to a US journalist who has been tracking the war in the east European nation.
At least 280 Russian armoured vehicles have been destroyed with the American Javelin missile, out of 300 shots fired, journalist Jack Murphy said in an article quoting a US Special Operations official.

That is a 93 per cent kill rate.
The Javelin, made jointly by Raytheon Missiles and Defence, and Lockheed Martin, follow a flight path that hits targets from the top, where the armour is relatively weaker. Almost every tank armour is thicker on the sides, but the top is known to be weaker, and that is where the Javelin missile strikes.

The Javelin can also be fired in a straight flight path mode, if needed.

"The first shipment of Javelins arrived (in Ukraine) in 2018, the weapons systems along with a training and sustainment block (called the Total Package Approach) totalling somewhere around $75 million," Mr Murphy wrote in the article.
As the Russians learned that Ukraine now had Javelins, their T-72 tanks in Donbas became less aggressive, and pulled further back from the frontlines," he said, quoting the US military official.

A single soldier can carry and operate the Javelin, though more hands would be needed to carry extra launch tubes.

When Russian armoured columns entered urban areas in Ukraine, their tanks became more vulnerable to Javelin hits if they didn't have infantry support. Ukrainian forces equipped with Javelins would hide and move quicker, as they didn't have a chance in a direct tank-versus-tank fight on open ground because of the sheer numbers the Russians have.
However, the numbers of tanks killed by Ukrainian soldiers, with the Javelin or other anti-tank weapons, are difficult to take seriously. Mostly appearing on social media, these numbers are likely to be exaggerated by the Ukrainians and downplayed by the Russians. The usual fog of war makes it even more difficult to ascertain accurate numbers.
Three days after the Russian invasion started in Ukraine, US President Joe Biden had instructed the US State Department to release up to an additional $350 million worth of weapons from US stocks to Ukraine, which had been asking for the anti-tank Javelin and anti-aircraft Stinger missiles.