BEIJING — On the surface, US President Barack Obama and Russian President Vladimir Putin are all niceties — a pat on the back here, a pleasantry there. But away from the cameras, the two leaders are circling each other warily at a global summit in China, coming face to face just as relations between their countries continue to deteriorate. Despite a handful of encounters so far, it was unclear whether the leaders had broached any of the tough issues — such as tough US sanctions that have damaged Russia's economy, or a fragile ceasefire in Ukraine that appears at risk of collapse. Officials said Obama and Putin didn't delve into substance during a brief encounter Monday night, and in public appearances on Tuesday, the two kept their deep-seated disagreements out of sight. Just outside of Beijing, where leaders from 21 nations were gathered for economic talks, picturesque Yanqi Lake became the venue for an awkward pas de deux between two of the most powerful leaders in the world. Entering an ornate, wood-paneled room for the start of the summit, Obama and Putin looked a bit like sidekicks to Chinese President Xi Jinping. The summit's host led the way, with the American on one side and the Russian on the other. “It's beautiful, isn't it?” Putin said in Obama's direction. Yes, it is, concurred a reticent Obama, avoiding eye contact with Putin and addressing his response to no one in particular. As the three presidents came to a stop at the head of the table, Putin reached out to give Obama a slap on the back. But Obama had turned in a different direction, and it didn't appear that the Putin's hand landed on its intended target. A few hours later, the two again found themselves in close quarters under an overcast sky as leaders planted trees in honor of their counties. Putin strode confidently up to his tree, ahead of Obama, who clasped his hands behind his back before picking up a shovel and greeting a Spanish TV crew with a wave. Away from the cameras, Obama and Putin did have a chance to speak privately, said a senior Obama administration official who wasn't authorized to comment by name and demanded anonymity. But it wasn't clear whether the leaders used that opportunity to address the vexing issues that have raised the specter of a return to a level of chilliness between the US and Russia unseen since the end of the Cold War. The US has been up in arms over Russia's presumed role in fueling pro-Russian rebels in neighboring Ukraine. White House officials have accused Russia of sending heavy weapons to the separatists and shelling Ukrainian troops, and have denounced Russia's buildup of forces along the border. A truce reached in September between the rebels and Ukraine's government is teetering, destabilized by what the White House calls a “blatant escalation” by Russia and rebel-organized elections in eastern Ukraine that the US condemned as a “sham.” Vice President Joe Biden, in a phone call last week with Ukraine's president, vowed further US sanctions against Moscow “if Russia continued to willfully violate the terms” of the cease-fire. Russia's economy has taken a major hit following US and EU sanctions — the ruble has plunged by a third this year and hit an all-time low last week — but Putin has dismissed the notion that he's hurting at the hands of the West. Addressing the Asia-Pacific economic summit here Monday, Putin said his government had the resources to stabilize its currency without taking any emergency measures. “We want Russia to play a different role,” Ben Rhodes, Obama's deputy national security adviser, said on Tuesday. “We want Russia to be a stabilizing force on issues that we care about. But they're not going to be able to do that ... if they've violating the sovereignty of a country next door.” Rhodes said Obama wouldn't not be seeking out a meeting with Putin while in Beijing — nor in Brisbane, Australia, where the leaders will once again run into each other over the weekend during a Group of 20 economic summit. “Putin knows where we stand,” Rhodes said, adding that Obama might seek to discuss Russia's actions with other G-20 leaders at the summit. For Obama and Putin, awkward encounters at international gatherings have become almost expected. But the optics of their meetings have gained even greater attention as the Ukraine crisis has taken center stage. In June, on the sidelines of D-Day anniversary commemorations in Normandy, France, Obama and Putin avoided each other during a group photo, with Obama even using Britain's Queen Elizabeth II as a buffer. The two later spoke briefly during a private leaders' lunch. And during a formal meeting last year during a summit in Northern Ireland, Putin slumped in his chair and sat stone-faced as Obama tried to make a joke about the Russian leader's athletic ability. Obama later said Putin frequently appeared to be “bored kid in the back of the classroom.” — AP