It can be difficult to understand what exactly is happening along the Russia-Ukraine border without knowledge of the countries’ deeply intertwined histories. That said, here’s everything you need to know:

What’s going on with Russia and Ukraine?

A build-up of Russian military troops along Ukraine and Russia’s shared 1,200-mile border has Ukrainian and Western officials fearful a repeat of 2014 (when Kremlin-led forces annexed the Crimean peninsula) is imminent. Moscow has denied any plans to invade Kyiv. U.S. intelligence, however, posits such an attack could happen as early as January 2022, though the current mass of troops lacks the support needed to sustain any sort of invasion. American officials have also accused Russia of “mounting an aggressive information operation to destabilize Ukraine politically,” with the plan to blame any escalation on Ukraine and NATO, writes CBS News.

Ukraine was a valuable part of the Soviet Union for centuries before becoming its own republic, having produced much of the wheat consumed in the U.S.S.R while acting as a sort of “buffer” between Europe and Russia. But ever since Russia annexed Crimea seven years ago, Ukrainian and Russian forces have been fighting a proxy war in the Donbas region of Ukraine. A peace deal in 2015 brought an end to most battles, though smaller skirmishes continue.

Given the cultural and ethnic ties between the two countries, Russian President Vladimir Putin has long maintained Ukraine falls under Russia’s sphere of influence, but has begrudgingly watched as pro-Western and anti-Russian sentiment blossomed over the years; in 2014, for example, Ukranians ousted a pro-Putin president and have chosen to elect Western-leaning politicians ever since. 

Putin wants both NATO and Western forces to back away from Ukraine, arguing their influence weakens his own and presents a threat to the Russian border. Though Ukraine is not a member of NATO, it is considered a “highly valued” organization partner — and the Kremlin wants assurance that status never sees an upgrade.

What could happen next?

U.S. officials are, at this stage, unsure whether Russia will forge ahead with an invasion, but they have not ruled out the possibility. On Monday, CIA Director William Burns warned that the build-up of military forces could allow Russia to act “in a very sweeping way.” The current assessment is that Russia might wait for the ground to freeze or for other European countries to be distracted with their own dealings to move in on Ukraine. But still, it’s unclear if Putin is actually planning to occupy Kyiv, or is instead simply posturing to win concessions from the West.

How does Ukraine feel about all of this?

Ukrainian President Volodymyr Zelensky believes Russia’s build-up sends a “very dangerous” message, and has said Ukrainian forces will respond if necessary. Ukranian officials have also asked the U.S. for weapons systems and capabilities they hope might stave off another invasion, considering the Russian military is far more robust than Ukraine’s — but that power balance would change with America’s help.

Also notable — support for joining NATO among Ukrainians reached 54 percent this year, up 40 percent since 2012 thanks in no small part to Putin’s attitude and messaging surrounding Ukraine.

What is the global community doing about it?

President Biden on Tuesday spoke virtually with Putin in an attempt at easing tensions and reaffirming America’s commitment to Ukraine’s sovereignty. It didn’t seem as though any real resolution was reached, other than Biden ruling out the possibility of unilaterally sending U.S. troops to Ukraine should Russia invade. Instead, the president warned Putin of severe economic consequences “like nothing he’s ever seen” should Moscow move on Kyiv. Biden said he’s “absolutely confident” Putin got the message.

National Security Adviser Jake Sullivan said the U.S. would also provide Ukraine with defense material, in addition to Russian sanctions, in the event of an invasion.

Internationally, Germany has indicated it would consider halting Nord Stream 2, the pipeline that will soon bring Russian gas to Europe, as a sanction if necessary. Newly-elected Chancellor Olaf Scholz said Tuesday that Germany was watching Russian movements “with great concern,” noting it “would be a completely unacceptable situation if Ukraine were to be threatened.” 

Biden also spoke with French, Italian, British, and German leaders on Monday, all of whom agreed to call on Russia to work to resolve the conflict in eastern Ukraine.

Was Biden’s Democracy summit related to any of this?

Sort of. The Biden administration hosted its inaugural Summit for Democracy on Thursday and Friday, joining forces with world leaders to address a backslide among democratic institutions worldwide. Russia and China were not invited. That the summit kicked off during a particularly contentious moment in Russia-Ukraine relations perhaps only underscored the administration’s message in organizing the virtual gathering — autocracies are on the rise, and it’s up to everyone else to help democracy prevail.

How does Biden handle Putin? Is it a strategy different from his predecessors’?

Biden has long disliked Putin, having proclaimed his distrust of the Russian president as far back as 2001. When Biden was vice president, he said he didn’t think the Russian had a soul. Nowadays, the commander in chief would like a “stable and predictable” relationship with Russia, and doesn’t seem to harbor any illusions of broad-scale cooperation.

Biden is so far the fifth American president to negotiate with Putin; and, notably, none of his predecessors “proved very effective at engaging with or containing” the Russian leader, writes The Washington Post. Though Putin temporarily ceded power during former President Barack Obama’s first term, the Obama White House praised his work and called for a “reset” between the U.S. and Moscow. The strategy wasn’t necessarily a success; things changed in 2014 when Russia annexed Crimea and the White House was forced to turn back toward economic sanctions.  

Former President Donald Trump, on the other hand, was criticized as being too soft on Russia and attempting to curry favor with Putin. Critics claimed he even prioritized Moscow’s needs ahead of his country’s own, despite his infamous “America first” ideology.

But Biden so far has evaded most criticism of his own — and some analysts say his general skepticism toward Putin and Russia has perhaps helped further the possibility of a “constructive,” “working” relationship between the West and the East.