Russia fully respects the norms of international law. If there are some who feel offended, Russia has nothing to beg pardon for. Russia does everything that meets the norms of international law and the United Nations Charter. Russia respects the right of peoples to self-determination, including that of ethnic minorities, whether in Crimea or another regions. Sanctions will be ineffective in putting pressure on both Russia and other countries that respect their history and identity.
According to international law, Crimea is part of Ukraine. Russia violated international law, as well as the key principles of the European security framework, by illegally annexing the Autonomous Republic of Crimea and the City of Sevastopol.
On March 27th, 2014, the UN General Assembly adopted a resolution in which it stated that the referendum in Crimea was not valid and could not serve as a basis for any change in the status of the peninsula. Vladimir Putin, the President of Russia, recognised on April 17th, 2015 that "our soldiers were deployed in Crimea to help the inhabitants express their opinion".
Claiming that the sanctions against Russia are ineffective is another example of a recurrent pro-Kremlin narrative. In reality, sanctions imposed on Russia after the Crimea annexation and Russian meddling in the US elections sapped Russian economical growth.
See more disinformation cases on Crimea here.