Short answer:

Long answer: Historically speaking Russia has always been expansionist and aggressive in it’s foreign policy. Because in all fairness it had to be in order to prevail and survive against foreign powers that sought to destroy or control them. Due to the fact that Russia lacks any defensive geographical boundaries, as they lay along the Eurasian Steppes and North European Plains, making them vulnerable to attack. The Russians were under the sway of the yoke of the Golden Horde, a Mongolian state, until through a series of wars managed to throw them off and liberate themselves to unify and form the newly created state of Russia. The Russians never wanted to experience that oppression ever-again, so from that moment forward, Russia always had to expand and be on the offense in all directions to create as much distance between them and their enemies.

They engaged in a series of conquests and wars over the course of centuries, subjugating the tribes of Siberia, conquered the Turkic and Mongol nomadic tribes of Central Asia descendants of the Golden Horde, and incorporated large swaths of Eastern Europe and the Caucasian region under their rule, after beating up their neighbors. They sent military expeditions into countries like Persia and China to protect their interests and gain access to warm-water ports and resources to fuel their economy. Fending off rival empires like the British, Japanese, Germans, Ottomans, and Swedes to hold onto their territory and crush internal dissent from their many minority groups, subjecting them to policies of Russification, where they force these cultures to assimilate into wider Russian culture and religion to promote stability and unity within the empire.

Then when the Russian Empire fell, it was succeeded by the USSR(Union of Soviet Socialist Republics) which lost portions of its territory to independent separatist movements and devastated from foreign interventions and a bloody civil war which claimed millions of lives, significantly hurting their economy. As a result for the next few decades, with some exceptions here and there, the USSR largely focused inward on itself, fearing another potential invasion from western powers seeking to destroy them, becoming defensive, focused on repairing their ruined economy with their collectivization programs and “socialism in one country” policy.

After the botched Nazi Invasion of the USSR and the ending of World War 2, the USSR begun to assert itself back onto the world stage, having occupied half of Europe, installing pro-Soviet governments, setting up as much of a buffer between them and the capitalist west. They begun to prop up and support allied governments across the world to challenge the capitalists, and spread their influence across the globe. Additionally they kept boosting military spending and nuclear armament to keep pace with the United States in case of a possible direct conflict, which inadvertently caused the Soviets to neglect other aspects of their economy, especially social spending, which begun to over-burden the Soviet economy and causing stagnate productivity.

Not to mention, infighting among the international socialists, like the Tito-Stalin split and more significantly the Sino-Soviet Split, due to ideological differences and competing economic interests lead to a giant rift in the socialist cause. Which the capitalist west exploited to further hamper the Soviet Union and it’s goals, inevitably contributing to its collapse in 1991 with minimal internal opposition, leading to the creation of 15 new republic's, the largest being the Russian Federation. However, the collapse of the USSR lead to a myriad of issues plaguing the fledgling nation, such as increased infant mortality, rising inflation and unemployment, the growing power of the oligarchs who created monopolies over their sectors of the Russian economy, decreased life expectancy and quality of life, as well as internal power disputes among the government and failure to crush the dissent in the Chechnya region lead to growing discontent among the population.

So Russia turned inward again, as the United States succeeded in becoming the world’s sole hegemon. For awhile relations between the two countries was cool and steady, with a few hiccups here and there. Russia focused on trying to re-establish itself and rebuild from the disaster that was the collapse of the USSR. The re-building process was difficult and stalled constantly due to government corruption and it’s inability to properly manage the economic crisis.

Then a former KGB agent and St. Petersburg mayor comes into the picture, his name is Vladimir Putin, a robust, shrewd, and cunning man who was determined to see that his nation was rebuilt. So when Russia’s unpopular president Boris Yeltsin resigned, Putin took the reigns of power and begun to commit to the re-forging of Russia’s society and it’s stance in the world. He defeated the Chechen separatists and warlords in Chechnya on the premise of restoring stability to the region and punish those responsible for the Russian Apartment Bombings. He made the oligarchs in Russia bend to his will, any who opposed him were systemically thrown out of power and arrested or died under “suspicious circumstances”. The economy begun to pick up again, employment was rising, the inflation rates were largely under control, infant mortality rates declined, the media solidified under the Kremlins control, and Putin started to modernize Russia’s outdated military.

But Putin kept up appearances, still maintaining a relatively friendly relationship with the West, he even became pals with then president of the USA George W. Bush.

That all changed in 2008 when Russia invaded the small country of Georgia to assist the local South Ossetia and Abkhazia separatists within the country, to not only establish reliable buffer states and military buses to further boost Russian influence in the Region but to prevent Georgia’s admittance to NATO(The North Atlantic Treaty Organization), which consists of the USA and dozens of her allied European countries.

You see in the years following the collapse of socialism in Eastern Europe, many formerly soviet-aligned nations joined NATO, itching closer and closer towards Russia’s borders, when the Baltic nations of Estonia, Lithuania, and Latvia join NATO in 2004, it became increasingly concern that it would become surrounded on all sides by its enemies and threaten the Russian heartland. So to prevent this encirclement, Russia invaded Georgia, establish a presence just within reach of it and a significant base of influence within the region to thwart its attempts to join NATO, as that could risk the possibility of all-out nuclear war. The Russo-Georgian War lasted only for 12 days but it send shock waves across the international community, as it served as Russia’s way of telling the world, it was no longer a dilapidated state but a mighty country seeking to re-assert itself on the global stage to challenge American global hegemony.

This corresponded with the rise of China as an economic juggernaut desiring to usurp the USA as the dominant global power and re-shape the entire geo-political order to revolve around them. So Russia and China found a mutual adversary that stood in the way of achieving their goals, so they begun to form military and economic pacts between them to ensure mutual cooperation and foster development in Eurasia to undermine American dominance, like the Shanghai Cooperation Organization and Belt and Road Initiative. As well as serving as an additional security measure to make sure Russia had reliable allies to protect it and maintain it’s spheres of influence in the region’s they’re invested in.

Tensions kept escalating when Russia invaded Crimea in the aftermath of the Ukrainian Euromaidan revolution in 2014, when pro-Russian president Viktor Yanukovych was deposed and moved to Russia in exile. Fearing a more-European aligned Ukraine could lead to them joining NATO thus undermining their influence and the loss of their only warm-water port in Sevastopol, as well as concern over the interests and rights of the large Russian minority population within Ukraine, lead to them invading Crimea to secure their vital position in the Black Sea and keep Ukraine in check, despite the international sanctions and condemnation. They also directly assisted Russian separatists in the Donetsk and Luhansk oblasts, arming and supplying the rebels in direct opposition to the new Ukrainian government, leading to a war that’s still ongoing and in perpetual stalemate. But it served it’s purpose well by maintaining a buffer between Russia and Europe and ensure Russian national security within the time being.

Russia also has been diplomatically and militarily aiding the Assad Regime and their allies(like Iran and Hezbollah) in the ongoing Syrian Civil War, bombing Syrian rebels, sending troops on the ground, and to disrupt both American and Turkish influence within the country to keep a vital ally in the region and maintain their only port in the Mediterranean sea.

They’ve also been reluctantly assisting the “president” of Belarus Alexander Lukashenko, again to assist as an effective buffer state between Russia and the West, but relations between the two states always had been uneasy in the best of times, yet still useful so long as Lukashenko stays in power, which might not be the case within the next few years or so.

They’ve also been assisting and directly supporting the Maduro regime in Venezuela, a Latin American nation practically in America’s back yard, lending money, men, materials, arms, and diplomatic support as leverage to gain a foothold in the western hemisphere and undermine American influence.

There’s also the infamous Wagner Group, a private Russian military organization(aka Mercenaries) with direct ties to the Kremlin, essentially serving as Russia’s invisible military hand in conflicts around the world, such as Syria, Venezuela, Sudan, South Sudan, Central Africa, Ukraine, Libya, Armenia, Madagascar, and Mozambique.

Russia also has some of the best cyber teams in the world, whether that be hacking the Pentagon, inferring with American and European elections, promoting far-right and far-left politicians through misinformation and bots to sow discord and disunity among the western liberal democracies, these Russian web brigades are some of(if not the) best examples of cyberwarfare in the world.

However, what Russia is doing right now isn’t nothing new, it’s current policy isn’t so much expansionist as it is “defensive”, Russia like in the past doesn’t want to be humiliated and subjugated, so they commit to policies and actions to keep as much distance as possible between themselves and its enemies. Whether it be the Great Game in Afghanistan, the Iron Curtain, or the modern conflicts around the world, it is just Russia trying to defend itself against foreign powers that seek to destroy it.

If I had to summarize current Russian foreign policy it’s that a good offense is a good defense, they’re being cautiously aggressive, meaning they want to act tough but not in a way that would result in direct conflict with the west and start World War 3 and end all of humanity in a blaze of nuclear hellfire. Rather they and their allies are seeking to undermine America’s global hegemony and establish their own regions of control. Russia is rising to the status of a great power, nevertheless, I doubt Russia can sustain this ascendancy for very long, Putin is gonna resign and no worthy successor has been chosen or considered, and the economic ramifications of the international sanctions are taking a toll on the Russian economy, dissent is already beginning to show in Russia as of late, combined that with the looming threat of climate change and demographic collapse, and you got a recipe for disaster waiting to happen.

Because usually across history states reliant on strong-men types eventually fall in one way or another and generally don’t last as long. But I guess we have to wait and see what comes next, don’t we?