As usual, the Russian government is playing a tough game with the US and its Western allies over Syria, with the revelations in late May that it plans to deliver advanced S300 anti-aircraft missiles to the Assad regime, along with a reported ten new MiG fighter planes. Yet while voicing criticism of these deals, the Obama administration has been welcoming a series of senior Russian officials to Washington, and Britain has actually softened its relations with the Russian government in recent weeks. Why is the Kremlin getting away with this?

One reason is that US officials—and their European counterparts—are loath to upset ties with the Russians in the run-up to the Syrian peace conference, which the Obama administration is trying to convene this summer with Russian support. But just as telling may be Washington’s newly-declared cooperation with Moscow in fighting terrorism, prompted by the April bombings in Boston. In recent weeks, the US has taken part in series of high-level meetings with Russian security officials, ostensibly in an effort to address shared terrorist threats. Yet for the regime of Vladimir Putin, the rapprochement might be seen to justify its longstanding use of powerful counter-terrorism tools to abuse human rights and to give new legitimacy to its own deeply problematic security services.

In fact the Russians hardly deserve the praise they have received from US authorities for their alleged help in the Boston bombing case. As the official story goes, as long ago as 2011, Russian authorities made the magnanimous gesture of warning the US about Tamerlan Tsarnaev, the elder of the two alleged bombers, and US authorities ignored the warnings. But the more information that comes out about Tamerlan and his brother, Dzhokar, also accused of the bombings, the clearer it becomes that Russia’s actions concerning the Tsarnaevs, whose father was from Chechnya, were at best self-serving.

In 2011, after learning about Tamerlan’s possible radicalism from the Russians, the FBI interviewed him but found nothing that raised concerns. Moreover, FBI requests to Moscow for further information about the man, such as what grounds the Russians had for thinking he might be a threat, were met with silence. Yet we have learned that in early 2012, unbeknownst to the FBI but well after the Russian authorities first raised suspicions about him, Tamerlan traveled to Russia and stayed there for six months. He had no US passport and his Russian passport had expired. Apparently he was carrying a passport from Kyrgyzstan, where he had spent much of his life before moving to the US in 2003.

Under these circumstances, Russian authorities would have followed Tamerlan’s every move during his trip, especially since he spent much of his visit in Dagestan and Chechnya, both considered breeding grounds of Islamic radicalism. It is a well-known fact that the Russian FSB (successor to the KGB) has infiltrated all the major rebel groups in these two territories. If, as numerous reports have claimed, Tamerlan was regularly meeting with Islamic rebels in 2012, the FSB would have been aware of it. Russian authorities also would have known that he then returned to the US. Yet the Americans were told nothing about Tamerlan’s trip, or his meetings with radicals.

Instead of raising questions about Russia’s file on Tamerlan, US officials have gone out of their way since the bombings to thank Moscow for its help in fighting terrorism and welcome Russian security officials in Washington. All this has played into the Kremlin’s hands and helped reinforce its longstanding arguments that the Chechen rebels it has been fighting in a brutal counter-insurgency for years are part of a larger al-Qaeda-led group that has the goal of international jihad.

Consider what has happened in recent weeks. The head of the Russian Ministry of Internal Affairs (MVD), which oversees domestic crime-fighting, Vladimir Kolokoltsev, traveled to Washington, where he met with US Attorney General Eric Holder, Head of Homeland Security Janet Napolitano, and FBI chief Robert Mueller. All three US officials, according to public reports of the meetings, supported more cooperation with Russia in the area of security and law enforcement. Mueller even promised to share FBI files with the Russians, saying that “such resources could be useful to Russian law enforcement agencies in view of the Sochi Olympics.

Meanwhile, Russian National Security Council chief Nikolai Patrushev also visited Washington and met with Barack Obama to deliver a letter from Russian President Vladimir Putin. Patrushev and Obama reportedly discussed the importance of “deepening counter-terrorism cooperation“ between Russia and the US.

But Patrushev, a close associate of Putin since their years together in the KGB, is the man who headed the FSB from 1999 until 2008. During that time the FSB conducted brutal counter-terrorist operations in the North Caucasus, in Chechnya in particular, and committed well-documented atrocities against civilians. The FSB has also been widely suspected of actual complicity in terrorist attacks, such as the Moscow apartment bombings in September 1999, which killed over 300 people. (Senator John McCain made a point of calling the evidence that the FSB orchestrated those bombings “credible.”) If there is anyone who should be on the so-called Magnitsky List—the list issued by the US Congress in April of Russian officials who are forbidden to enter the US because of human rights abuses—it is Patrushev.

Some US lawmakers are unhappy with the way the Obama administration has handled the Boston Marathon case and want to see further investigation of the many unanswered questions about Russia’s surveillance of the Tsarnaevs. This week a delegation led by Rep. Dana Rohrabacher, a California Republican, traveled to Moscow with that purpose in mind. But it is unlikely that Russian law enforcement officials will add much to what is already known. And the Obama administration, which has already faced criticism for not heeding the early Russian warnings, is unlikely to pursue the matter forcefully.

If the Obama administration can be faulted for reaching out too readily to the Kremlin, then its European counterparts deserve equal criticism. The British government, for example, has had frosty relations with Moscow ever since the November 2006 murder in London of Alexander Litvinenko, the exiled former FSB officer who had been a strong critic of the Russian government. Litvinenko, it will be recalled, died after receiving a lethal dose of radioactive polonium, which he apparently ingested during a meeting with two Russian agents at a London hotel. The agents in question, Andrei Lugovoi and Dmitry Kovtun, fled back to Russia, where Lugovoi became a member of the Russian parliament. The Kremlin has consistently refused Britain’s request for Lugovoi’s extradition.

Yet suddenly, in early May, following a discussion about Syria with Putin, British Prime Minister David Cameron had warm praise for the Russian president. And then two weeks ago a coroner in London, Sir Robert Owen, upheld a request from British Foreign Secretary William Hague to withhold from the public inquest into the Litvinenko murder crucial documents relating to Russia’s involvement. As one former colleague of Litvinenko expressed it,

It’s obvious: the government is trying to protect its relations with Putin. They have their reasons. They want Russian co-operation and investment. But in this case, it’s being done at the expense of justice…They [Hague and Cameron] appear more concerned about chemical weapons in Syria than polonium spread around the streets of London.

The West’s overriding priority right now is to enlist the Kremlin in achieving some progress on Syria. US Secretary of State John Kerry has been negotiating in Paris with Russian Foreign Minister Sergei Lavrov to arrange a peace conference in Geneva this summer. But these efforts, while compromising US abilities to deal robustly with Moscow, already show little promise of success.

Quite apart from Moscow’s arms deals with Assad, it should be clear that the Putin regime has a strong desire to prevent Assad’s fall from power. For one thing, the Syrian government ensures Russia’s continued status in the Middle East as a regional power. Russia and Syria have strong trade and military ties that date back to the Soviet period. In 2011, for example, Russia exported approximately $1 billion worth of arms to Syria. And Russia also has a naval base in Syria, Tartus, which gives it a crucial strategic presence in the Mediterranean Sea.

But the Kremlin’s Syrian interests are directly related to its domestic security concerns, too. The possibility of Sunni extremists stepping into a power vacuum left by the Assad regime, is deeply threatening to Moscow, which has fought two wars in Chechnya to subdue Sunni-led separatists. In fact, there are already reports that, as Moscow reasserts its support for Assad, significant numbers of Chechen fighters have joined rebel units in Syria.

Putin’s government has managed to persuade the West to forget, for the moment, Moscow’s role in fomenting terrorism by its brutal suppression of Chechnya, where innocent people have died in the hundreds of thousands since the mid-Nineties. In fact, the parallels between Chechnya and Syria cannot be lost on Putin. As Russia expert Fiona Hill observed in March:

For Putin, Syria is all too reminiscent of Chechnya. Both conflicts pitted the state against disparate and leaderless opposition forces, which over time came to include extremist Sunni Islamist groups. In Putin’s view—one that he stresses repeatedly in meetings with his U.S. and European counterparts—Syria is the latest battleground in a global, multi-decade struggle between secular states and Sunni Islamism…

As the Kremlin faces a rapidly growing Muslim population at home—one that is economically distressed and harbors deep resentment against Moscow—it is doubtless worried that Russia could be next.