LONDON -- President Donald Trump on Sunday teased what he said would be a "big day" as Ukrainian President Volodymyr Zelenskyy and a host of European leaders prepared for a White House meeting that Trump said can end Russia's invasion of Ukraine "almost immediately." Monday's Washington, D.C., summit follows Trump's meeting with Russian President Vladimir Putin in Alaska on Friday. Since that meeting, Trump appears to have dropped his demand for Russia to agree to an immediate ceasefire and is now pressuring Kyiv to accept territorial concessions to secure a peace deal. On Sunday, Trump explicitly said Ukraine will not regain Crimea -- occupied by Russia in 2014. The president also repeated that Ukraine will not be allowed to join NATO, though White House special envoy Steve Witkoff and Zelenskyy have hinted at alternative security guarantees involving the U.S. "President Zelenskyy of Ukraine can end the war with Russia almost immediately, if he wants to, or he can continue to fight," Trump wrote on social media on Sunday. The president has previously incorrectly framed Ukraine as the initiator of the conflict, which began with Russia's full-scale invasion in February 2022. That invasion followed Moscow's cross-border aggression in 2014, which saw Russia seize Crimea and parts of the eastern Donbas region. "Big day at the White House tomorrow," Trump added. "I've never had so many European leaders at one time. It's my great honor to host them!!!" "NO GOING INTO NATO BY UKRAINE," Trump added. "Some things never change!!!" Trump is expected to greet Zelenskyy outside the West Wing at 1 p.m. ET, according to a schedule published by the White House, after which they will hold a bilateral meeting. The president is scheduled to take photos with European leaders at around 2:30 p.m. ET and hold a multilateral meeting with them at 3 p.m. Zelenskyy said in a post to social media that he had arrived in Washington on Sunday night, expressing his gratitude to Trump for hosting the planned meeting. "We all share a strong desire to end this war quickly and reliably," Zelenskyy wrote. "And peace must be lasting," he added, noting Moscow's 2014 aggression plus the failure of the international community to enforce the 1994 Budapest Memorandum -- which was also signed by Russia -- that offered Ukraine "security assurances" in exchange for Kyiv surrendering its Cold War-era nuclear arsenal. "Ukrainians are fighting for their land, for their independence," Zelenskyy wrote. "Russia must end this war, which it itself started. And I hope that our joint strength with America, with our European friends, will force Russia into a real peace." MORE: Russia ceasefire refusal 'complicates' talks, Zelenskyy says before White House visit Friday's summit in Alaska ended with Russia demanding that Ukraine cede the entirety of its contested and fortified eastern Donetsk region in exchange for an end to the fighting, two sources told ABC News. Trump then challenged Kyiv to "make the deal" and lavished praise on Putin. "Look, Russia is a very big power, and they're not," Trump told Fox News after the meeting. Putin, he added, is a "strong guy" and "tough as hell." A host of European leaders will accompany Zelenskyy at the White House meeting. European leaders have backed Zelenskyy and Ukraine's positions during the Trump administration's pressure campaign on Kyiv. Those confirmed as attending are European Commission President Ursula von der Leyen, German Chancellor Friedrich Merz, British Prime Minister Keir Starmer, NATO Secretary-General Mark Rutte, French President Emmanuel Macron, Italian Prime Minister Giorgia Meloni and Finnish President Alexander Stubb. Ahead of last week's summit in Alaska, European leaders echoed Zelenskyy's position that a ceasefire must precede peace negotiations, that security guarantees for Kyiv must be put in place and that only Ukraine can make the final decision on any territorial concessions. On Sunday, French President Emmanuel Macron told reporters that he and his fellow European leaders will be traveling to Washington both to support Zelenskyy and "to defend European interests" at a "very serious" moment for the continent's security. "If we are weak today with Russia, we prepare the wars of tomorrow," Macron said, adding that Moscow had "never" respected past "promises of non-aggression." The nature of Western security guarantees for Ukraine will be a key topic for discussion, Macron said, explaining to journalists a two-pronged approach by which Ukraine's military would be bolstered and a Western "reassurance force" would be deployed to Ukraine to act as a deterrent against renewed Russian attacks. Any concessions will spark intense debate within Ukraine. The country's constitution dictates that any changes to the national borders must be approved by an all-Ukraine referendum. Kyiv's ambitions to join both NATO and the European Union are also enshrined in the constitution, meaning it may need to be amended for Ukraine to accept exclusion from either bloc. MORE: Ukrainian soldiers focus on daily battles as Trump and Putin prepare to meet "Territorial concessions are impossible," Oleksandr Mrezhko, a member of the Ukrainian parliament and chair of the body's foreign affairs committee, told ABC News. "Under the present circumstances, we need a ceasefire and security guarantees to prevent Putin from violating the ceasefire." "In my opinion, Putin's idea about a 'peace treaty' instead of a ceasefire is extremely dangerous and unacceptable for both Ukraine and the U.S.," he added. "That the U.S. offers to be engaged in security guarantees is great news for us, but we don't know yet what it will be in practice," Merezhko said. "I personally continue to believe that the best option for all -- Ukraine, the U.S. and the EU -- is NATO membership for Ukraine." "Putin is afraid of only one thing -- NATO," Merezhko added. "That's why it's the most reliable and effective security guarantee for us." MORE: Why Ukraine's ex-foreign minister believes Putin won't go for peace as Trump summit approaches Meanwhile, both Russia and Ukraine continued long-range attacks overnight into Monday. Ukraine's air force said Russia launched 140 drones and four missiles in the country, of which 88 drones were shot down or suppressed. Missile and drone impacts were reported across 25 locations in Donetsk, Kharkiv, Sumy, Dnipropetrovsk, Odesa and Kyiv regions, the air force said. At least seven people, including a child, were killed when a Russian drone impacted an apartment complex in Kharkiv, local officials said. Zaporizhzhia Gov. Ivan Fedorov said in a post to Telegram that at least three people were killed and at least 20 people injured by missile strikes in the southern region. Russia's Defense Ministry said its forces downed at least 24 Ukrainian drones overnight. ABC News' Tom Soufi Burridge and Kelsey Walsh contributed to this report.