It seems like the war in Ukraine is on the brink of escalating to a new level. North Korean troops have joined Russia on the battlefield, Ukraine is striking deep into Russian territory with US-provided weapons, and the Kremlin is yet again making nuclear threats. These developments intensify the sense that this war could spiral out of control. Paradoxically, however, they may also help usher in its end.

In October, North Korea added 11,000 troops to the battlefield on Russia’s side. The Biden administration said this were an unacceptable escalation. Over the weekend, it approved Ukraine’s use of US-provided missiles for long-range strikes into Russia. Russia responded with a new and more threatening nuclear doctrine that says it might use its nuclear arsenal against a non-nuclear country – a not-so-thinly veiled threat to Ukraine.

Russia has made nuclear threats several times during the war, and I have argued that the west must take these threats seriously, no matter how inconvenient and immoral they may be. Still, these latest threats seem like pure posturing given the fact that the announcement was long expected, and Russia is now making steady headway on the battlefield with conventional means.

Joe Biden’s decision to allow Ukraine to strike into Russia with long-range Atacms, which could result in European governments removing similar restrictions on the missiles they have provided Ukraine, is more important. It’s also more risky.

This is first time US weapons are being used to destroy targets inside Russia itself and a significant step toward a direct conflict between the two major powers. It’s no surprise that Russia has repeatedly said it would view these long-range strikes as a direct Nato attack on Russian territory. Russia may have just cut internet cables deep in the Baltic Sea in response and could escalate in other ways, such as by providing military aid to the Houthis or US adversaries elsewhere in the world.

The US president has thus rightly kept Ukraine on a tight leash to date when it comes to the long-range missiles the US has given it. But the war’s strategic context is changing, both in the US and on the battlefield. Allowing Ukraine to use the Atacms may in fact be worth the risk if it improves the Trump administration’s chances of bringing this war to an end.

In the United States, Donald Trump is now waiting in the wings. He has promised to end this war “in a day”. In reality, any serious negotiation will require months of focused diplomatic spadework around the world – with US allies, partners and adversaries, as well as with Russia and Ukraine. There are complex issues of how peace can be guaranteed that will not be resolved quickly or easily.

The balance on the battlefield has also changed. Whereas Volodymyr Zelenskyy’s maximalist and unachievable war aims were once the main obstacle to negotiations, Russia’s battlefield success is now as much of a hurdle for diplomats. That success has rekindled hope in Moscow that it may be able to capture Ukraine’s capital, Kiev. The appetite has grown with the eating, as some in Russia have noted.

In this context, the more cards the incoming US administration has to pry a ceasefire out of Russia the better. Biden’s decision to remove the restrictions on the Atacms hands Trump a useful card that should encourage the Kremlin to take the diplomatic path sooner rather than later.

It may not be enough, however. Even though the Biden administration was right to move with caution in permitting these strikes into Russia, it means that Russia has had the chance to develop defenses against these weapons in the meantime. The best way to do more would be for Biden to impose even tighter sanctions on Russia, which Trump could then offer to lift during ceasefire negotiations.

Russia is already under heavy sanctions, but it has adapted to them and thereby reduced the leverage they offer the west. Now that inflation is under control, it is possible to tighten sanctions on Russian oil and gas. To be effective as negotiating leverage, however, these sanctions must be designed so that the White House can easily remove them in return for Russian concessions.

To be sure, how Trump’s plans to end the war are still murky. A reasonable objective would be a ceasefire that preserves Ukraine’s sovereignty and the prospect that it may one day join the European Union – even if not Nato. But the Cabinet Trump has named is a mix of attitudes about Ukraine and Russia. Some, such as Tulsi Gabbard, might be satisfied to just cede all of Ukraine to Russia. Others, such as Marco Rubio and Michael Waltz, are likely to want a more hard-nosed approach.

If faced with the prospect of a major Russian victory early in his administration, even Trump may prefer a tougher line with the Kremlin – if only to avoid the optics that Biden suffered during the withdrawal from Afghanistan.

Just weeks after Trump takes office, the war in Ukraine will enter its fourth year. Soon after that it will have lasted longer than the US was in the second world war. Hundreds of thousands have died and millions of lives have been shattered. Security in Europe has not been improved by the fighting. Globally, the war has encouraged a dangerous, tightening bond between Russia, China, Iran and North Korea. The Kremlin is still to blame for the war, but for the sake of the US, Europe, and the world, it’s time to start taking serious steps to bring it to an end.

• Christopher S Chivvis is a senior fellow and director of the Carnegie Endowment’s American statecraft program