Russians fire back at Ukrainian positions in Kursk, Russia.Russian Defense Ministry Press Service via AP PhotoUkraine's incursion into Kursk has entered its third week, and there's no sign it's letting up.Zelenskyy has suggested his troops will dig in to make a "buffer zone" at the border.Experts outlined the risks Ukraine faces at this stage in the offensive.Ukraine seized the initiative with its offensive in Kursk earlier this month.The incursion into the western Russian territory — now into its third week — has jolted an increasingly apathetic set of Western allies back to attention while bringing the war to Russia in a dramatic fashion.Ukraine has also seized prisoners and, for however long, land, both of which offer leverage in future negotiations.The offensive has also produced issues for Russian forces, some of which have been hastily redeployed into Kursk from critical battlefronts in Ukraine.Even with few insights into Kyiv's exact goals, there's a lot for Ukrainians to cheer on.But the offensive has also committed sorely needed elite troops to a herculean effort at a time when the main front seems already stretched to its limit.Business Insider contacted several experts and asked them where and how this offensive could backfire on Ukraine in the coming weeks.It could be another grinding stretch of front line to defendUkraine's ultimate goals for this new offensive still aren't clear.On Sunday, President Volodymyr Zelenskyy said he intended the action to create a buffer zone in the Kursk region as part of a wider goal of limiting Russia's war capabilities.Ukraine has already shown signs of digging in, setting up a HQ in the region and saying it's destroyed several bridges that are key for Russian supply lines.When it comes to the incursion, Ukraine has also "more explicitly tied this to forcing President Vladimir Putin to enter talks or end the invasion" Matthew Savill, military sciences director at the Royal United Services Institute, told Business Insider."This raises the stakes and may result in them committing beyond a sustainable position," he said.The main risk, Savill said, is that if Ukrainian forces try to hold the territory in the long term, they naturally lengthen the war's front line — and will need to be able to reinforce and protect it just as much as the rest of the front.Ukraine will be forced to defend this line just as doggedly as it has been doing everywhere else, he said.Media reports suggest that the Kursk effort has already pulled in some Ukrainian troops from the Donbas — a stretch of the main front line that was already under significant pressure."That could result in a short-term gain, for long-term disadvantage," Savill said.Ukraine could lose crack troops and equipmentPatrick Bury, a military analyst at the UK's University of Bath, told BI that Ukraine is "committing elite brigades, with good Western kit."Those brigades include the storied 80th Air Assault Brigade, which has undertaken key operations in Bakhmut and Kherson.Ukraine can ill afford to lose them.A worst-case scenario for Ukraine is if Russia pins elite troops down in Kursk with greater firepower to be "mauled," Bury said."That's the worry, that they get fixed, and the Russians eventually over time wear them down, they end up losing a significant part of their capability, and then be forced to withdraw," he said.Faced with that scenario, Ukraine could pull back to a more defensible position, losing ground but preserving vital troops, he said."The ultimate bargain, the ultimate decision Ukraine will have to make is how many losses are they willing to take to these elite brigades to hold how much land?"Bury remained optimistic about Ukraine's calculus here.He suspects that Ukraine had already made a close projection on what troops Russia was going to be able to bring to bear on Kursk — and is now making a calculated gamble that it's not enough to crush them there.Ukraine looks like it will lose an important eastern cityIt's unclear whether the redeployment of some forces to Kursk has affected Ukraine's ability to defend the main, 600-mile front line in the east of the country.But what is clear is that, independently of the Kursk situation, Russia was already creeping closer to the critically important town of Pokrovsk in the Donbas region."You get to Pokrovsk, and it looks to me that you probably cut the supply lines to a number of different armies," said Matthew Ford, a war expert and lecturer in international relations at the UK's University of Sussex.Ford described Pokrovsk as a "central spoke" for Ukrainian logistics.As of Tuesday, the head of the city's military government has ordered its evacuation, saying people have two weeks to get out before Russian troops arrive.One apparent goal of the Kursk offensive was to thin out Russian troops along the main front line — and multiple reports indicate that Russia has redeployed forces from places including Crimea and Zaporizhzhia, Bury told BI.But it doesn't look like those redeployments have been at the expense of the advance on Pokrovsk, he said."The rate of the Russian advance on Pokrovsk has increased since the Kursk op," he added.Bury speculated that ceding ground in this way may have simply been part of a wider Ukrainian plan — much of which, as the surprise Kursk offensive has made plain, is under an impressive veil of secrecy.Savill said that ultimately, a lot depends on the extent to which Russia's President Vladimir Putin decides to throw troops into the Kursk situation.Putin could decide to simply "contain" the situation in Kursk with a minimal commitment of forces while still being able to press home his advantage in Pokrovsk, Savill said.In this scenario, Russia gains a key city from Ukraine while forcing Ukraine to commit even more resources to defending its buffer zone in Kursk.Would Putin go nuclear?After previous attacks on Russian soil, Putin or his proxies have pointed menacingly at their nuclear arsenal.Russia's nuclear doctrine allows for their use when the country's sovereignty is under threat.But no such warning has come since the Kursk offensive, and Bury is skeptical that this is on the table for now."The fact that there's been absolutely nothing and no hint of using a tactical nuclear missile as a result of Ukraine rolling Western tanks into Russia shows you that it's highly unlikely," Bury said.Ford agreed that the offensive shows that "Russian red lines on nuclear use aren't quite as red as we thought."Even if Ukraine withdraws from Kursk in the coming weeks, the offensive will have produced some serious upsides, he added.Ukraine's efforts have refocused Western attention on the war — "that's quite handy," he said.Ukraine also hasn't lost significant numbers of troops yet — and has gained POWs to trade in the future, he added.And it has reminded Western leaders that they can coordinate a sophisticated military surprise capable of embarrassing Putin, he said."And does it matter after that whether they stay in Russia or not?" he asked.