Joe Biden has called newly graduating US military officers the “guardians of American democracy” at a commencement speech at the elite West Point military academy in New York state, where the US president, without mentioning Donald Trump by name, gave strong warnings of unprecedented threats to US freedom.

Biden, speaking in front of about 1,000 graduating cadets at the US army training academy on Saturday, urged the newly minted officers to “hold fast” to their military oath “not to a political party, not to a president but to the constitution of the United States of America, against all enemies, foreign and domestic”.

In remarks that could be seen as a thinly veiled reference to the threat to democracy Biden believes Trump poses to the US as the two candidates battle for the White House in this November’s election, the president said that the oath taken by the military is “as important to your nation now as it ever has been”.

“From the very beginning, nothing is guaranteed about democracy in America. Every generation has an obligation to defend it, protect it, preserve it – now it is your turn,” said Biden, who cited the right to vote, the right to worship and the right to protest as key freedoms that require “constant vigilance”.

The president said that the US was founded on an idea of equality but that “ideas need defenders to make them real and that’s what you, the class of 2024, are all about. The defenders of freedom, champions of liberty, guardians – and I mean this – guardians of American democracy. You must keep us free at this time, like none before.”

Biden outlined a global situation that he said had placed unprecedented challenges upon the US military, warning that the cadets are “graduating into a world like none before … There’s never been a time in history when we’ve asked our military to do so many many different things in so many different places around the world, all at the same time.”

The president reaffirmed that the US will continue “standing strong” with Ukraine in the face of a “brutal tyrant” in the form of Russian leader Vladimir Putin, although again reiterated no US troops will be sent to the conflict.

Biden said that the Nato alliance was “stronger than ever”, praised the US military for its efforts in erecting a pier and delivering air drops to provide aid to Palestinians suffering amid Israel’s war in Gaza, and said that the US was “standing up for peace and stability” regarding the threat posed by China to Taiwan.

“The upshot of all of this, across vastly different regions and very different challenges, our men and women in uniform are hard at work strengthening our alliances,” Biden said, adding that the military was “standing up to tyrants and safeguarding the peace and protecting freedom and openness. We are doing what only America can do, as the indispensable nation.”

Biden is scheduled to participate in Memorial Day services at Arlington National Cemetery in Virginia on Monday. A week later, he will travel to Normandy, France, to participate in ceremonies marking the 80th anniversary of the D-day invasion.

Biden is expected to give a major speech about the heroism of Allied forces in the second world war and the continuing threats to democracy today.

On Saturday, he made his first address at West Point as president, having twice addressed a graduating class of cadets when he was vice-president. The elite training academy is about 40 miles (65km) north of New York City.

Trump, the presumptive Republican nominee to run against Biden in the 2024 election, was the last president to speak at a West Point commencement, in 2020.

College campuses nationwide have erupted in sometimes-violent protests over Biden’s support for Israel’s war against Hamas following the militant group’s 7 October attack on southern Israel. Students have used commencement speeches at colleges such as Harvard, Duke and Yale universities to protest Biden’s actions, but no such demonstrations were expected at West Point and the commencement passed without incident.

The West Point military academy was founded in 1802 by then president Thomas Jefferson to train army officers, and it has produced some of the US’s greatest generals, including two who went on to become president.

Trump, meanwhile, has seen some of his support from the military community erode. In 2016, he won 60% of voters who said at the time that they served in the military, according to exit polls conducted by NBC News.

That figure dropped to 54% in 2020, according to NBC News. In 2020, Biden won 44% of voters who said they served in the military, according to the data.

Reuters contributed reporting