Andrzej Duda made the statement at an international security conference, Warsaw Security Forum, on Tuesday.
"At the moment here in Poland we're experiencing hybrid aggression in the form of attempts by the Belarusian services to push migrants into EU territory," the president said.
"We're defending Nato and EU borders with full determination," Andrzej Duda went on to say, adding that Poland had confirmed that people with terrorist links are among those trying to cross the country's border from Belarus.
The president said that new security challenges have emerged on the horizon, including China's "multi-dimensional actions in technology, economy, finance and cyberspace”.
"This is coupled with new, breakthrough technologies whose acquisition by our adversaries may disturb the existing order," the president said, adding that terrorist threats have not gone away, either.
Turning to Russia, Andrzej Duda said the country is increasing its global military involvement, threatening Nato not only from the east, but also from the north and south. He also accused Moscow of hybrid actions aimed to undermine the stability of the democratic institutions of the West and its election system.
Commenting on the role of the United States, the president said the West needed "an America that is politically and militarily involved in the security of Europe as well as being active in Nato."
According to Andrzej Duda, "this is a guarantee for the democratic world to be able to meet numerous challenges, both those close to our borders and the ones in distant parts of the globe."
The Warsaw Security Forum is an international conference hosted by the Casimir Pulaski Foundation, an independent, non-partisan think-tank specialising in foreign policy and international security. (PAP)