Three reasons Putin will march into eastern Ukraine. And three he won’t.

Will he or won’t he?

Concerns are growing that Russian President Vladimir Putin may be preparing to launch a lightning military strike into eastern Ukraine, as US military officials report suspicious increases in the number of Russian troops amassed on the Russian-Ukraine border.

Even President Obama has gotten into the speculation about Mr. Putin’s intentions, saying in an interview with CBS News released Friday that the Russians might “simply” be trying to “intimidate” Ukraine’s struggling interim government – “or it may be that they’ve got additional plans.”

Calling on Putin not to “revert back to the kinds of practices that … were prevalent during the cold war,” Mr. Obama urged the Russian leader to “de-escalate the situation” and “move back” Russian troops from the border.

But also on Friday, Putin called Obama, and the two leaders discussed ways to forge a “diplomatic path” for resolving the Ukraine crisis. The two presidents agreed to have their top diplomats – Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov – meet soon to discuss what the White House called a “de-escalatory approach" to the crisis.

So what is Putin up to, and what will be the deciding factor in whether or not he sends troops into Ukraine? No one knows for sure, with some analysts saying the Russian leader might not yet have decided, or that he may have changed his mind in recent days. For others, the intense guessing game seizing the West may be one objective the former KGB officer can already check off his list.

Amid the uncertainty, some factors stand out to suggest that Putin will – or won’t – flout the US, Western Europe, and the international community (the United Nations General Assembly declared Thursday, with a 100-to-11-and-58-abstentions vote, that Russia’s annexation of Crimea is illegal) and move to seize eastern Ukraine.

Key reasons he will:

• Putin believes ethnic Russians in eastern Ukraine are under constant and growing threat.

The Russian Foreign Ministry issues regular reports of Russian-speaking Ukrainians coming under attack in the country’s heavily Russian-speaking east (reports that Ukrainian and Western officials say are bogus) and on Friday a top Russian security official lumped Crimea and Ukraine’s eastern provinces together in a Kremlin ceremony marking Russia’s absorption of Crimea.

Alexander Malevany, deputy chief of the Federal Security Service, told Putin that “the lawful desire of the peoples of Crimea and eastern Ukrainian regions is causing hysteria in the United States and its allies.”

• Putin has assessed the West’s appetite for “crippling sanctions” on Russia and has determined that Russia can withstand whatever modest steps the West is likely to take. He has also interpreted US pledges not to defend Ukraine’s sovereignty militarily as a green light.

• Putin has never considered that Ukraine is a “nation” or a real country, rather that it is part of Russia with Russians and Ukrainians being one people. In 2008 Putin is said to have told then-President George W. Bush – who supported Ukraine’s eventual accession to NATO – “Do you understand, George, that Ukraine is not even a state?”

But now with Ukraine’s interim government having just signed an association agreement with the European Union, and national elections set for May, Putin sees it as “now or never” for bringing eastern Ukraine under the wing of Mother Russia.

Key reasons he won’t:

• Putin already got what he wanted. Annexing Crimea has accomplished two of Putin’s goals – delivering a PR coup at home and weakening and destabilizing a Ukraine with Western-leaning aspirations – without running the risks that an incursion deeper into Ukraine would entail.

• The broad, sector-wide sanctions the West has pledged to impose on Russia in the event of further moves into Ukraine would aggravate Russia’s already stagnant economic conditions.

The modest sanctions the West has imposed on Russia so far have struck Putin as laughable – he made a point of publicly delighting in opening an account in the one Russian bank the US has targeted with sanctions. But the sanctions the US and especially the European Union are promising to impose on key Russian economic sectors – metals and mining, banking and finance, defense industries, and above all, energy – would be a different story.

• Putin’s real goal is to reassert Russia as a power to be reckoned with, especially in its backyard comprised of the former Soviet space. And he’s accomplished that without the headache of a foreign invasion that might go as well as the seizure of Crimea, or very well might not.

Putin – seething every time the president of the United States refers to Russia as a “regional power” – wanted a return to a cold-war scenario that elevated Russia and reaffirmed its place as a power to be reckoned with.

And with the world now appearing to hang on Russia’s every move and military deployment – instead of focusing (when it did consider Russia) on his hunting exploits and shirtless horseback riding – Putin, to a certain degree, has already got what he wanted.