Upon arrival in Brussels on Sunday, Pence said he looked "very much forward" to his meetings with EU foreign policy chief Federica Mogherini, European Council President Donald Tusk, European Commission President Jean-Claude Juncker and Nato Secretary General Jens Stoltenberg.
Brussels follows a visit to the Munich Security Conference, where Pence told European leaders and defence experts: "The United States is and will always be your greatest ally.
"President Trump and our people are truly devoted to our transatlantic union."
Trump's criticism of Nato as "obsolete", his praise for Britain's decision to leave the European Union, and his apparent tilt to Russian President Vladimir Putin have unnerved US allies.
[caption id="attachment_47919" align="aligncenter" width="800"] AFP
And they continue to seek reassurance from Washington even though Pence, US Defence Secretary James Mattis and US Secretary of State Rex Tillerson hewed close to seven decades of transatlantic policy during their foray into Europe.
Pence said Washington would push Russia to honour the Minsk ceasefire accords in Ukraine and Tillerson said the US would only cooperate with Moscow if it benefits the American people.
But French Foreign Minister Jean-Marc Ayrault said he was "struck" that Pence had never mentioned the EU, which raised doubts after Trump welcomed Brexit and appeared to hope other EU states will follow suit.
Mogherini has said Pence's visit is "a very important political sign," though she suggested EU-US relations may become more pragmatic and less automatic than before.
During her visit to Washington 10 days ago, Moghehrini warned Trump's administration not to "interfere" in European politics amid fears it supports the breakup of the 28-nation EU.
Addressing fears that businessman Ted Malloch might be named the next US ambassador to Brussels, Mogherini said she had been told "there is no decision taken and no specific name considered at this point."
In the German and British press, Malloch reportedly said Brexit was a harbinger of the EU's eventual disintegration, and he has compared the bloc to the Soviet Union.
Tusk and Juncker, who will also meet the new vice president for the first time, have also expressed concerns about Trump.
Juncker said after Trump won the election that he feared the new president will implement everything he said he would during a "campaign that I found absolutely disgusting."
While Pence's meetings with EU and Nato leaders are likely to be diplomatic, several groups plan to hold demonstrations against Trump policies.