"This seems to me to be a political, diplomatic reason. The Javelins are a very effective platform."
He said the weapons cost about a million dollars each and were now in short supply.
"The Javelins are made in one factory in Iowa and the demand for them has outstripped the productive capacity of the factory."
Buchanan said Henare could be relaying views of Defence Force leaders who would've argued there was little chance of Kiwi troops needing to use Javelins anytime soon.
He said Nato members were enthusiastic about helping Ukraine with lethal aid but New Zealand wanted to maintain some foreign policy independence.
And in a postwar environment one day with Russia-Europe relations strained, New Zealand might want to act as a mediator, he said.
"People in Mfat might be thinking about the post-conflict environment where New Zealand might be a good interlocutor or go-between."
National security expert and Army veteran Dr Jim Rolfe said the rest of Cabinet might be following one of two lines of thought.
"One is, someone doesn't like the word 'lethal' because New Zealand doesn't do lethal, New Zealand does humanitarian assistance and disaster relief."
Another possible view was that New Zealand had so few Javelins or other so-called "lethal" material, the country couldn't give them up.
Rolfe, a former security adviser to the Department of the Prime Minister and Cabinet, said it might be naive for New Zealand to imagine it could act as future mediator.
"I'm sure someone will suggest it, but someone in Norway will have suggested it as well."