Murray Polner is HNN’s senior book review editor and a blogger.

When all the biographies, memoirs and histories are written about Barack Obama’s foreign policy legacy it will be a mixed one, ranging from the indulgent because of complex and unsolvable challenges to disappointed assessments from the idealistic left and also from the confrontational right. Personally, I liked how David Bromwich once portrayed him after five years of his presidency: “The world’s most important spectator.”

“Obama has a larger-spirited wish to help people than any of his predecessors since Jimmy Carter,” Bromwich began, “though caution bordering on timidity has kept him from speaking.”

Well, not quite anymore, given his new-found courage in finally taking on Netanyahu and his congressional bootlickers who’d love to see the USAF level Tehran but also avoid a land invasion we would surely lose even if Israel joined in. As a prudent warning once went, “If you liked Iraq, you’ll love Iran.”

Obama’s legacy will also be positively burnished with his move to undo the too-long, ideologically-grounded isolation of Cuba while the US simultaneously befriended death squad and neo-fascist El Presidentes south of the border. Remember them?  Argentina, Brazil, Chile, Peru, Guatemala, Honduras, Nicaragua, and Cuba’s Fulgencio Batista.

But there’s also a worrying side to Obama’s legacy, specifically the risky games he’s playing with Putin’s increasingly Tsarist Russia, where both sides have a huge pile of ready-to-use nuclear bombs and where, without any debate or concern outside of the Imperial City’s political class, the US has now become deeply involved in a revived East-West battle. In 2014-15, the US and NATO gifted to Kievan Ukraine, a dysfunctional and corrupt state whose current politicians assumed power after an American-supported coup, military, political and financial aid with which to fight Russia’s breakaway Donbas proxy.

It is precisely in Eastern Europe that Obama fits Bromwich’s portrayal of him as a “spectator.”  Some of his State Department people behave like virtual free agents, with Obama muttering scripted, supportive lines. State’s leading neoconservative regarding Ukraine is Victoria Nuland, whose husband Robert Kagan is a major DC neocon.

Meanwhile, if there is any coherent plan about Eastern Europe in particular and Ukraine in general, it is to establish a cordon sanitaire circling Russia. It didn’t work in 1941-45 and it won’t work now, even though NATO’s Article 5 could lead a former Soviet satellite like NATO members Latvia or Lithuania -- and presumably, one day, Ukraine, if the neocons have their way -- to claim it had been attacked and then invoke Article 5, whereby the US is obliged to come to the aid of any attacked member nation.

Make no mistake. The US is now an active player in regions Russia views as an integral part of its sphere of influence. As if the hopeless, insolvable mess in the Middle East isn’t enough of a burden, the US has recently sent 300 US soldiers from the 173rd Airborne Brigade to Ukraine for six months to “train” Ukrainian soldiers.  In another move barely known if at all to John and Mary Doe, Americans and Bulgarians will hold joint Balkans military drills, while NATO ships prowl the Black Sea, Russia’s sole warm waterway and home to its fleet in Sevastopol, Crimea. This led Aleksandr Grushko, Russia’s envoy to NATO, to warn of his country taking “necessary countermeasures.” (American tanks and more than 120 armored components have also been shipped free of charge to Latvia.) More ominously, Putin’s press secretary warned that “The participation of instructors or specialists from third countries on Ukrainian territory” could destabilize the present fragile truce between eastern and western Ukraine. Not to mention Putin’s not so veiled threat about nuclear war.

What ever happened to diplomacy? Melvin Goodman, a former CIA analyst recently proposed in the NY Times nothing less than negotiations to cool everyone down and avoid provoking a still-powerful Russia in its own backyard. “Isn’t it time to recognize the ‘existential’ importance of Ukraine to Russia,” asked Goodman, “to prevent the worsening of the crisis and to ensure continued cooperation in the arms control arena as well as conflicts in the third world?”

This may sound like Munich-style appeasement to our Washington-based “ostentatious warmongering” base – as Christian Lorentzen, a British editor put it -- but as Henry the K. offered, regular condemnations of Putin are no substitute for a  coherent, well-considered policy. While dispatching air patrols, shipping sophisticated war materials and piles of free money to former Warsaw Pact states, and providing potentially inflammatory “training” exercises may not be Act One of a future Big War, it could lead to an unintentional or deliberate incident or alibi (Sarajevo in 1914, Poland in 1939, Korea in 1950, Tonkin Gulf in 1964, Bush’s WMDs in 2013) causing a war, possibly nuclear, which will surely blow Obama’s legacy, and the rest of us, to hell.