U.S. President Joe Biden departed Sunday on a five-day trip to Europe, heading first to Britain. He then travels to Lithuania for a NATO summit in Vilnius, before making a final stop in Finland to meet with Nordic leaders.

In London, Biden will have meetings with British Prime Minister Rishi Sunak and King Charles to discuss various bilateral issues and climate financing for developing nations.

Just a month ago, in Washington, Biden and Sunak agreed to an “Atlantic Declaration” and committed to collaborating on advanced technologies, clean energy, and critical minerals. Biden hosted Sunak at the White House.

At the NATO summit, Western leaders will discuss their latest efforts to bolster Ukraine’s fight against Russia along with Sweden’s bid to join the West’s main military alliance. Twenty-nine NATO nations support the bid over the objections of members Hungary and Turkey. Efforts by Ukraine to join the bloc will also be on the agenda.

In an interview taped last week, Biden told CNN he thinks it is premature to call for a vote on Ukraine joining NATO.

“I don’t think it’s ready for membership in NATO,” Biden said. “I don’t think there’s unanimity in NATO now …in the middle of a war. If the war is going on [and Ukraine was a NATO member], then we’re all in the war. We’re at war with Russia,” since NATO’s charter calls for all its members to defend any individual country when it is attacked.

As it stands, leaders of the NATO countries will discuss the state of Ukraine’s slow-moving counteroffensive to recapture territory in the southeastern part of the country that Russia took in the earliest stages of 16 months of fighting.

NATO countries, led by the United States, have sent billions of dollars in armaments to Ukraine, but Russian aerial bombardments have continued to kill dozens of Ukrainian civilians even as Kyiv’s forces have shot down hundreds of incoming missiles. The ones that landed have killed people and destroyed residential buildings.

After the NATO summit, Biden heads to Helsinki, the Finnish capital, to commemorate Finland recently joining the military alliance created in the aftermath of World War II, and to meet with Nordic leaders.

NATO Secretary-General Jens Stoltenberg met with Biden at the White House last month, days after Biden hosted Britain’s Sunak. Biden and Stoltenberg pledged their continued support of Ukraine in its war against Russia.

“The NATO allies have never been more united. We both worked like hell to make sure that happened. And so far, so good,” Biden said as he sat alongside Stoltenberg, whose term as NATO leader has been extended for a year.

Finland joined NATO in April, effectively doubling the length of Russia’s border with the world’s biggest security alliance. Biden has characterized the strengthened NATO alliance as a sign of Moscow’s declining influence.

Sweden is also seeking entry into NATO, although alliance members Turkey and Hungary have yet to endorse the move. Biden last week hosted Swedish Prime Minister Ulf Kristersson at the White House as a show of support for Sweden’s bid.

Turkish President Recep Tayyip Erdogan has said Sweden is too lax on Kurdish terrorist groups and security threats, while Stoltenberg has said Sweden has met its obligations for NATO membership by toughening anti-terrorist laws and other measures. Hungary’s reasons for opposing Sweden have been less defined, with officials in Budapest complaining about Sweden’s criticism of democratic backsliding and the erosion of the rule of law. Hungary, however, has said it will approve Sweden’s NATO membership bid if Turkey assents.

All NATO nations have to ratify the entry of new member countries.