Joe Biden has been blowing hot and cold. Last week in a call with Russian President Vladimir Putin, he was making a renewed case for constructive diplomatic talks. But by Friday, he had unveiled harsh new sanctions against Moscow.

The measures, among the most extreme options available to Washington, ban American financial institutions from directly purchasing Russian sovereign debt, in response to unproven allegations that Moscow sought to meddle in the 2020 US presidential election. While President Vladimir Putin’s spokesman, Dmitry Peskov, insisted on Friday that the country’s economy remains “robust” despite the move, Biden’s intentions were clear – to signal to a domestic audience that he can ‘talk tough’ on Russia.

Few would have doubted, however, that Biden is capable of taking a confrontational stance with the country or its president. Relations between the two are still reeling from a series of comments he made about his Russian counterpart in an interview with the ABC news network, in which he was asked whether he believed Putin was “a killer.” “I do,” he replied.

Politicians in Moscow lined up to slam the remarks, which some described as an attack on the whole nation, while the White House refused to be drawn on whether Biden was speaking literally or metaphorically. In the wake of the row, Russia recalled its ambassador, Anatoly Antonov, for crisis talks with officials on the state of relations.

Deputy Foreign Minister Sergey Ryabkov explained earlier this month that Moscow was in no hurry to send Antonov back to his post “in the coming few days,” but that instead “the timings will be determined based on what steps Washington plans to take on the bilateral track.” For full diplomatic representation to resume, he said, the Americans would have to demonstrate “a desire to at least relatively stabilize our relationship and… do something visible and noticeable in this regard.”

It has now been a month since Antonov returned to Moscow, leaving Russia without an ambassador in the US at a time when tensions are rising rapidly. As well as the imposition of sanctions, an increasingly tense situation in eastern Ukraine, where Kiev’s forces have fought a series of bloody clashes with two separatist republics, has risked sucking both countries into a new military conflict. Russia has stationed troops on the border in response to increased NATO activity, and Ukraine has requested the US-led bloc ramp up its presence in the region.

That lack of diplomatic representation only worsened last week, as Washington moved to expel 10 of Moscow’s envoys alongside introducing the new economic restrictions. In a reciprocal move, Russia declared that the same number of American representatives would have to return home. In short, at a time when ties are fraught, and misunderstandings potentially catastrophic, fewer channels for communication exist between the US and Russia than in the past.