He said this after a meeting with U.S. Secretary of Defense James Mattis in Kyiv on Thursday, an Ukrinform correspondent reports.
"The discussion of these issues requires silence until the final decision is made," Poroshenko said.
According to him, at the meeting with Mattis he discussed "all aspects of our cooperation with the United States, including the extension of our defense capabilities and cooperation, in particular, in the military-technical sphere."
Poroshenko recalled that during his visit to the United States the sides had agreed on an active dialogue on ensuring the defense capabilities of Ukraine.
"This concerns not only supplies of lethal weapons, but also the provision and increase of defense capabilities, including the means of electronic warfare, the means that increase the effectiveness of our Armed Forces in the defense sector," he said.
At the same time, he believes that the provision by the United States of defensive weapons to Ukraine could have been a strong motivation for Russia to stop its aggression.
"This would only increase the chance of defending [Ukraine] if Russia decided to attack my territory, my troops. This would be a very strong motivation to stop these irresponsible steps," Poroshenko said.
At the same time, he said he was satisfied with the results of his current meeting with the Pentagon chief.