Europe pushed Monday to toughen its response to Russia’s invasion of Ukraine, with Sweden following Finland in deciding to seek NATO membership and European Union officials working to rescue proposed sanctions that would target Russian oil exports helping to finance the war.

On the ground, Ukrainian troops resisted attempted Russian advances and even rolled back front lines. In a small but symbolic boost for Ukrainian morale, a patrol of soldiers recorded triumphant video of their push to the Russian border in the region of Kharkiv. Ukrainian forces have already driven Russian troops back from the region’s capital, reducing their ability to hit the battered city with artillery.

As fighting raged, international efforts to respond to Russia’s aggression continued to pick up pace. Swedish officials announced their intention to seek NATO membership — following a similar decision from its neighbor Finland. Those are seismic developments for the Nordic countries that have traditionally positioned themselves as militarily “nonaligned.”

Russian President Vladimir Putin has looked grimly upon the alliance’s post-Cold War expansion in Eastern Europe, seeing it as a threat. But if the invasion was meant as a check on NATO, it appears to have backfired — by driving Sweden and Finland into NATO’s arms and pushing members of the alliance to send massive shipments of weapons to Ukraine.

Yet the Russian leader on Monday seemed to brush off that setback, saying “there is no direct threat to Russia created by the expansion involving these countries.”

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“But the expansion of military infrastructure onto this territory will of course give rise to our reaction in response,” he said.

NATO’s secretary-general, Jens Stoltenberg, has said the membership process for both Finland and Sweden could be very quick — though member Turkey has cast some doubt over the move.

Swedish Prime Minister Magdalena Andersson said Monday that joining the 30-member military alliance was her country’s best defense in the face of Russian behavior.

“Unfortunately, we have no reason to believe that the trend (of Russia’s actions) will reverse in the foreseeable future,” she said.

In addition to sending military aid to Ukraine, Europe is also working to choke off funding for the Kremlin’s war, by reducing the billions of dollars it spends on imports of Russian energy.

But a proposed EU embargo on imports of Russian oil faces opposition from a small group of countries led by Hungary, which is one of a number of landlocked countries that are highly dependent on the imports, along with the Czech Republic and Slovakia. Bulgaria also has reservations.

“We will do our best in order to deblock the situation,” EU foreign policy chief Josep Borrell said. “I cannot ensure that it is going to happen because positions are quite strong.”

Western weapons deliveries to Ukraine and sanctions against Russia have helped the outgunned and outnumbered Ukrainian forces slow the Russian advance — and even turn it back in places.