After spending much of the last two years offering virtually unadulterated praise for Vladimir Putin, Donald Trump finds himself with limited options as he prepares to confront the Russian president for the first time Friday. On the campaign trail, Trump made warmer relations with Moscow a centerpiece of his foreign policy, and he remains committed to forging a stronger alliance with Russia against Islamic terrorist groups. But realpolitik and political reality have conspired to stymie the president’s best-laid plans for a U.S.-Russia détente. Embroiled in an ever-expanding Justice Department probe into whether his campaign coordinated with the Russian government during the presidential election last fall, and facing increased pressure from both Democrats and Republicans in the Senate, Trump can’t risk making concessions to Putin without inciting a fresh wave of scrutiny back home. He also faces a complex series of challenges over Syria, where tensions between the U.S. and Russia have neared a boiling point after an American fighter jet shot down a Syrian plane that was attacking U.S.-allied forces. Russia has since vowed to treat any U.S. coalition aircraft west of the Euphrates as a potential target.

The biggest risk may be what Trump says when he meets Putin face-to-face on the sidelines of the G20 summit in Hamburg this week, in an unscripted setting where anything could happen. Aides are expected to accompany the president during the official meeting, to help manage the encounter. But foreign policy experts still worry that Trump—a political neophyte highly susceptible to flattery—will be easily outmaneuvered by Putin, a former K.G.B. officer with decades of experience in global affairs. The Russian president is “professionally prepared to try to manipulate people,” William Burns, a former U.S. ambassador to Russia under George W. Bush, told Bloomberg. “He will come well-equipped, and it’s important that we do that too.”

A number of delicate diplomatic issues will fill the air between Trump and Putin when they meet in Germany, including the growing North Korea nuclear threat, rising tensions in Syria, and Russia’s annexation of Crimea. But perhaps the most pressing issue is the one that Trump has vigorously avoided acknowledging or addressing: the allegation that the Kremlin interfered in the 2016 presidential race, and the retaliatory sanctions that the Obama administration imposed on Russia in the wake of the election. The White House may be ignoring the “crime of the century”, but Putin, it seems, is not. For weeks, Moscow has been ratcheting up the pressure on the Trump administration to return two alleged Russian spy compounds, in Maryland and Long Island, which President Barack Obama ordered vacated at the end of last year. On Monday, Putin’s foreign affairs adviser Yuri Ushakov warned that Moscow’s patience “has its limits” in regards to the rollback of the sanctions. And while Trump has repeatedly characterized Russian meddling in the election as “a hoax” and the F.B.I. investigation into his campaign’s potential involvement a “witch hunt,” the political ramifications of returning the compounds to Russian control would be severe. In the weeks since Trump fired James Comey—a move the president reportedly told Russian officials had removed the pressure on his administration—the Justice Department investigation has widened, and the potential optics of making concessions to Putin have only worsened. “The president is boxed in,” Nicholas Burns, who served as U.S. ambassador to NATO under Bush, told The Washington Post. “If you try to curry favor, offer concessions, pull back on the pressure, he’ll take advantage. He’ll see weakness in a vacuum.”

If Trump did move to return the suspected spy compounds to Russia, as his administration has reportedly considered doing, he would almost certainly face renewed pushback on Capitol Hill. After the White House signaled in May that the properties might be on the table as a bargaining chip in Syria, the Senate passed a bill that would effectively strip Trump of his authority to roll back Obama’s sanctions without Congressional approval. And while a similar piece of legislation has met greater resistance in the House, the issue is far from resolved. Silence from Trump on the Russian interference in the election would also likely be met with criticism. “The president needs to confront Putin on the Russian intervention in our elections, and we will not accept it in any way if he just sweeps it under the rug,” Adam Schiff, the top ranking Democrat on the House Intelligence Committee, told Bloomberg. “I’m afraid the message Putin will take away is that he doesn’t have the courage to stand up to him.”