"We have fully supported, are supporting and will continue to support Ukraine," Lithuania's Chief of Defence Valdemaras Rupsys said in a statement.

"Weapons and technology are nothing without the knowledge and ability to use them, so... we will share our knowledge and experience."

Vilnius delivered the short-range Stinger missile systems to Ukraine on Sunday after Washington approved the transfer of American weapons to Kyiv amid mounting tensions.

The troops will train their Ukrainian counterparts "for the next few weeks", according to Lithuania's armed forces.

The Baltic NATO member's troops are also taking part in a training mission in western Ukraine.

With more than 100,000 Russian troops massed on the Ukrainian border, there is concern that a major conflict could break out in Europe.

But Russia said Tuesday it was pulling back some of those forces to their bases, prompting cautious optimism in the West of a possible first major step towards de-escalation.