You dodge the question: Russia and Ukraine signed a peace agreement in 2015 to end the civil war. Russia held to that agreement. Ukraine did not.

No shots were fired by Russia when they annexed Crimea. In 2013 - one year prior!!! - the Guardian (IIRC) sponsored a referendum in Crime by a western-backed polling group and an overwhelming number of Crimea residents wante to join Russia. That is why there was no violence when Crimea was annexed by Russia.