The shock appearance happened under immense secrecy, with Biden taking off from Joint Andrews Base at 4:15 am local time. U.S. officials had expressed concerns that Biden couldn’t fly into Ukraine or take a ten-hour train ride without immense risk to the host nation or himself. Ensuring the president’s safety was a near-impossible endeavor, those officials said, though they acknowledged Biden had long wanted to go Kyiv.

But now Biden is in Kyiv for an eighth time, flanked this visit by a handful of staffers, including national security adviser Jake Sullivan. “Each time more significant,” Biden said.

A scheduled trip to Poland provided the opportunity to visit Ukraine as president, and the caution was ultimately set aside. Biden marked the one-year anniversary of the war by walking the streets of Ukraine’s capital — the same city Russia tried to seize 12 months ago — and meeting with Zelenskyy.

As the two men toured Kyiv, air raid sirens went off in the Ukrainian capital. Still, the message of his visit was clear: Ukraine is safe enough for an American president to visit despite the missile strikes, drone attacks and trench warfare initiated by Vladimir Putin.

In a statement after his arrival, Biden said that Putin “thought Ukraine was weak and the West was divided. He thought he could outlast us. But he was dead wrong.”

In a joint address with Zelenskyy, the U.S. president announced a new, half-billion dollar weapons package that will include artillery ammunition and anti-armor systems like Howitzers and Javelins, as well as sanctions “against elites and companies that are trying to evade or backfill Russia’s war machine.”

Zelenskyy, who has been pushing for the West to send longer-range missiles to hit faraway Russian positions inside Ukraine, said he and Biden spoke about “the weapons that may still be supplied to Ukraine even though it wasn’t supplied before,” though he did not provide details on commitments.

Zelenskyy also said he looked forward to conversations with Biden about “what we have to do to stop the war, to have success in this war … and how to win this year.”

Biden had been under immense pressure to visit Kyiv from Republicans, Democrats and foreign counterparts. Zelenskyy has received multiple sitting European leaders and American lawmakers, making Biden’s absence more conspicuous with each passing month.

Reports started to circulate ahead of the visit that Biden was on his way as security preparations became obvious in and around the Ukrainian capital. U.S. military jets were seen circling near the Polish border and Kyiv residents posted videos on social media of lockdowns in the city center and near the U.S. Embassy.

The trip to Europe was designed to coincide with the one-year anniversary of the war, with Biden set to denounce Putin’s incursion and publicly declare that the United States will support Ukraine until the final moments of the conflict. His physical presence in Kyiv could be one of the enduring legacies of his war-anniversary trip.

It’s unclear how or if Putin will retaliate. There is already widespread fear that he would mark the one-year anniversary on Feb. 24 with a show of force, such as by ordering a larger barrage of missile strikes on Ukraine.

Following his stop, Biden is set to fly to Warsaw where he’ll deliver a speech Tuesday to celebrate Ukraine’s remarkable resistance and the West’s collective defense of the targeted country. It’s a reprise of his address in Poland last year about how the United States aimed to partner with allies to help Ukraine. The most memorable line of the speech, however, was what appeared then to be a call for regime change in Russia: “For God’s sake,” he said, “this man cannot remain in power.”

Veronika Melkozerova contributed to this report from Kyiv.