A US citizen has been detained on suspicion of espionage in Moscow, Russia's security service says. The citizen, identified as Paul Whelan, was detained by the Russian security service and now faces between 10 and 20 years in jail, the Russian state-linked Tass news agency said on Monday. "On December 28, 2018 staff members of the Russian Federal Security Service detained US citizen Paul Whelan in Moscow while on a spy mission," the security service's public relations centre said. The organisation did not say where Mr Whelan was being held or what the specific activities involving espionage were. A criminal investigation is now underway, news agency Interfax said, citing the security services. The US Embassy in Moscow was alerted about the detention in line with the bilateral consular convention, RIA Novosti reported, citing the Russian Foreign Ministry’s press office. The embassy has not yet issued a statement. The detention comes amid a period heightened tension between the US and Russia, particularly in relation to the use of spies. Earlier this month, Maria Butina, a Russian gun enthusiast pleaded guilty to being an unregistered foreign agent. Butina said in court she had been acting on behalf of the Kremlin, befriending senior National Rifle Association leaders and influential conservatives. The Russian President Vladimir Putin said he did not understand why Butina was detained and that he would support her. Relations between the United States and Russia have been muddied in recent years amid accusations of cyber espionage, nuclear proliferation and Russia aggression against the international system, despite the US having one of the friendliest presidents to Russia in decades. The United States security services have accused Russia of hacking the Democrat National Committee during the 2016 presidential election, and of running a coordinated social media disinformation campaign. But US President Donald Trump has taken a softer stance, taking Mr Putin's pleas of innocence at face value. The Russians said last week that they had built a hypersonic nuclear-capable missile, which he said could avoid a US-built missile shield. Mr Putin said in a New Year letter to the US president on Sunday that Moscow was ready for dialogue on a "wide-ranging agenda," the Kremlin said. <strong>_______________</strong> <strong>Read more:</strong> <a href="https://www.thenational.ae/world/europe/putin-says-russia-is-ready-to-deploy-new-hypersonic-nuclear-missile-1.806794"><strong>Putin says Russia is ready to deploy </strong></a><strong><a href="https://www.thenational.ae/world/europe/putin-says-russia-is-ready-to-deploy-new-hypersonic-nuclear-missile-1.806794">new</a></strong><a href="https://www.thenational.ae/world/europe/putin-says-russia-is-ready-to-deploy-new-hypersonic-nuclear-missile-1.806794"><strong> hypersonic nuclear missile</strong></a> <strong><a href="https://www.thenational.ae/world/mena/russia-says-syria-s-assad-is-popular-likely-to-win-re-election-1.806783">Russia says Syria's Assad is popular, likely to win re-election</a></strong> <strong><a href="https://www.thenational.ae/world/mena/russia-the-us-should-transfer-its-territory-in-syria-to-assad-1.806626">Russia: The US should transfer its territory in Syria to Assad</a></strong>