Ukraine's defense minister Ihor Tenyukh has explained why Ukraine's armed forces are not fighting back against the Russian occupation of Crimea - since Russia has not admitted that its forces are in the peninsula, there is no de jure open aggression, and therefore Ukraine has no legal right to offer armed resistance. A second reason is that no state of martial law has been declared in Ukraine - so the use of armed force would be a criminal offense, and would be treated as an attack on Ukraine's own people.
Tenyukh also said that the armed forces never considered the danger from Russia, and that to prepare for a confrontation with such a large and powerful adversary would require a great deal of time and money.
On the eastern border Russia has 220,000 military personnel, 150 aircraft, 60 ships, tanks and other armored vehicles - a force several times greater than that of the Armed Forces of Ukraine. The Armed Forces of Ukraine have only tactics and fighting spirit. We have put all the armed forces on a state of combat-readiness in accordance with the plan of exercises. But the statistics are not reassuring."
Of 41,000 ground troops only 6,000 are really ready.