Did Russia violate international laws in Ukraine and if so, how?

There have been several claims since the Russian Federation attacked Ukraine the 24th of Feb that it violated international laws, and such claims have been made several times since the Crimea got annexed.

Did the Russian Federation violate any international law since 2014 in Ukraine? And if so, how?

EDIT: Here are some claims :

"Putin violates all international law principles" -- E. Macron, president of French Republic

"Russian President Vladimir Putin's decision to recognize the independence of self-proclaimed entities "LPR/DPR" is in breach of international law and a flagrant violation of the sovereignty and territorial integrity of Ukraine" -- B. Johnson, prime minister of UK

"This is a grave breach of international law & a serious threat to Euro-Atlantic security," -- NATO Secretary General Jens Stoltenberg