In a new episode of Political Wire's podcast, we spoke with Nicholas Burns, a longtime ambassador and now a professor at Harvard's Kennedy School of Government, about the Russia-Ukraine crisis and about the role that America should play as a world leader in the era of globalization.

Here are five takeaways:

1. We're not quite back into a Cold War, even if it seems as if we are. The media has continually suggested that America and Russia may have re-entered the Cold War in the wake of the Ukraine crisis. But the U.S. isn't in a protracted state of nuclear tensions with a communist superpower anymore. So it's a stretch to say that Cold War is back. But Burns said there are some echoes of it: "President Putin has used brute force to take over a piece of territory that wasn’t his. And he’s drawn new lines in Europe, so it feels a little bit like the Cold War that I remember back in the 1970s and 1980s."

2. Obama should toughen sanctions on Russia, but he's right not to pursue military action. Military action is simply a non-starter, Burns said. "Russia is a nuclear-weapons power. We are. It would be catastrophic to make this kind of a man-to-man duel, and the president wisely is not doing that." Burns also noted that the U.S. doesn't have a security commitment to Ukraine since the latter isn't in NATO. On the other hand, Burns argued, Obama could be more aggressive on the sanctions front. The current sanctions, consisting of travel bans for a couple of dozen Russian officials and bank-account freezes, just doesn't cut it, Burns said: "I don't think that Putin felt it was going to intimidate him in any way, and that's what you’ve got to do. You’ve got to make him pay economically, isolate him politically, there’s got to be a cost."

3. Trust is key in foreign relations. Putin's actions have shattered that trust for a long time. Trust "doesn't mean you agree on everything, but it means that when some leader tells you something that he or she is going to commit to do something for you that it’s going to happen," Burns said. Even though there was a modicum of trust between the U.S. and Putin after 9/11, that trust was damaged when Russia didn't follow up on its promise to work closely with the U.S., Burns lamented. Now, with the Ukraine crisis, that trust may never come back as long as Putin is in power. "How can you trust a leader now, like Vladimir Putin, who invades another country and then formally annexes it?" Burns said. "We haven’t seen this kind of blatant, brazen behavior since the 1930s in Europe." The loss of trust between the two nations could imperil their ability to work together on other high-profile matters such as the global economy and nuclear security.

4. The White House should reconsider its proposed defense budget cuts. In the weeks leading up to the crisis, the president proposed significant cuts to the Pentagon budget, including a reduction in the size of the Army to its smallest size since before World War II. But Putin's annexation of Crimea from Ukraine underscores why the U.S. still needs a strong military, Burns argued. "I really think the Obama administration now needs to reconsider that budget," Burns said. Maintaining a sizable military — the greatest in the world — will help the U.S. carry a more assertive presence in the world, particularly in Europe and Asia, he said. With the potential for Putin to continue pressing into Ukraine, "we have 16 European allies in NATO who are counting on us to be strong enough to deter whatever President Putin has in mind," Burns said. And China is asserting itself more aggressively in Asia and the Pacific. The U.S. is still the guarantor of peace in that part of the world, Burns said. "We can’t afford to have a military that’s so reduced in capacity that it can’t fulfill that mission," Burns said.

5. Embracing full-blown isolationism would endanger national security and economic prosperity. Burns is sympathetic to Americans who have grown weary of continual U.S. involvement in conflicts abroad. After all, the Afghanistan and Iraq wars have dragged on for more than a decade, costing thousands of American soldiers' lives and billions upon billions of dollars. Meanwhile, as the U.S. economy continues its slow but steady recovery, Americans feel the need to undertake more nation-building at home, Burns said. As a result, isolationist factions have been rising in both major political parties. But pulling ourselves back in the era of globalization is dangerous, Burns said. The world is "highly integrated, it requires a forward presence outside the United States of many of our troops to hopefully not to fight…but to safeguard peace," he argued. Moreover: "Our economy is all tied up in the economies of Europe and Asia."

Listen to the whole conversation here:

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