Perhaps not relating to periods of instability, but Venezuela has bought a lot of Russian arms and the two countries' militaries have in the past cooperated. From the Wikipedia page on Russia-Venezuela relations:
Under President Hugo Chávez, Venezuela has enjoyed warm relations with Russia. Much of this is through the sale of military equipment; since 2005, Venezuela has purchased more than $4 billion worth of arms from Russia. In September 2008, Russia sent Tupolev Tu-160 bombers to Venezuela to carry out training flights. In November 2008, both countries held a joint naval exercise in the Caribbean. Following Chavez's two visits to Moscow in July and September 2008, Russian Deputy Prime Minister Igor Sechin arrived in Venezuela to pave the way for a third meeting within five months between their two presidents.
And more recently:
In July 2017, during the crisis in Bolivarian Venezuela, in an article of Russia's Military-Industrial Courier, a journal popular with military officers of the Russian Armed Forces, in the event of a Venezuelan civil war, it was recommended that the Russian government provide military intelligence to the Bolivarian government, establish alliances with ALBA and to assist proxy leftist militant forces, such as colectivos, to maintain the Bolivarian government's power.