The US vice president maintained there is broad bipartisan support for the NATO alliance in the US, regardless of Trump. He called the US commitment to NATO a sacred honor that would always be upheld.
US Vice President Joe Biden reaffirmed the United States' commitment to the NATO alliance and its allies after meeting with leaders of the Baltic states in the Latvian capital, Riga on Tuesday.
He said the US remains committed to the collective defense of all NATO members, including those on its easternmost flank.
"I want to make it absolutely clear to all the people in (the) Baltic states: we have pledged our sacred honor, the United States of America... to the NATO treaty and Article Five," Biden, a Democrat, said in the Latvian capital.
"The fact that you occasionally hear something from a presidential candidate in the other party, it's... nothing that should be taken seriously," Biden said.
In addition to Trump's controversial remarks, the Baltic states - Lithuania, Latvia and Estonia - have been unnerved by recent acts of Russian aggression, most notably Moscow's annexation of the Crimean peninsula in 2014, as well as the ongoing separatist movement in eastern Ukraine that is backed by Kremlin.
The fighting there has claimed nearly 8,000 lives since April 2014.
Bipartisan support for NATO
"There is continued overwhelming bipartisan commitment in the United States of America in both political parties to maintain our commitment to NATO," he said.
The Democratic presidential candidate Hillary Clinton has a definitive but not insurmountable lead in opinion polls.
Lithuanian President Dalia Grybauskaite said she was confident that the US would continue to support the alliance wholeheartedly, regardless of who became the next president.
Russia accuses NATO of being an aggressor because of its eastward expansion. Taking in Poland, the Czech Republic and Hungary in 1999 was distasteful for the Kremlin, but the 2004 enlargement, which saw seven former Soviet bloc nations - including the three Baltic states - join the alliance was a particularly bitter pill for Moscow.
bik/jil (Reuters, AP, dpa)