March 4, 2022: -Hungary’s Viktor Orban, a longtime ally of Russian President Vladimir Putin and a thorn in the side of fellow EU leaders, has had a week of sharp reversals and swift political retreats.

After Russia recognized Luhansk and Donetsk as Russian-backed separatist-controlled regions in Ukraine, the EU starting work on an initial round of sanctions against Moscow. But there was one primary concern in Brussels: Will Hungary and its nationalist leader Orban approve them?

An EU official, preferring to remain anonymous due to the sensitive nature of the discussions, told CNBC in the previous week that it was a pivotal moment for Orban to show if he was loyal to Russia or the EU.

Fast forward a couple of days, and the response from Hungary’s prime minister has surprised many political experts and has been welcomed in Brussels.

“It is important that Hungary has joined and fostered EU unity,” another EU official, who preferred to remain anonymous, told CNBC on Tuesday.

Orban has often boasted of his close relationship with Putin. Speaking at a joint news conference in February, Orban referenced how they had worked together for the previous 13 years while adding that the two “have the longest memory of the European Union and Russia’s leadership,” according to Politico.

Close links were seen in the coronavirus pandemic, for instance. Hungary became the first EU nation to buy a Russian-made Covid vaccine even though European regulators didn’t approve it.

There have been commercial and energy deals, too. Over the previous decade, according to Eurostat, Hungary has been increasing its share of imports of Russian natural gas, from 9.070 million cubic meters in 2010 to a high of 17.715 million cubic meters in 2019.

But Orban has chosen the EU in the wake of the Russian invasion of Ukraine and has turned his back on Putin.

His government announced that Hungary would welcome Ukrainian refugees and support Ukraine’s EU membership application. This is on top of having approved, together with the other EU member states, demanding sanctions against Russian oligarchs and the Russian economy.

“Orban is an opportunist. Putin’s future support is very uncertain and might not play well with his electorate. He would get very little out of siding with Russia these days. This is the reason he goes along with the sanctions,” Daniel Gros, distinguished fellow at the think tank CEPS, told CNBC through email.