A Japanese daily says the fuel North Korea used to power its rocket seems to be similar to fuels used in China and Russia.

The Asahi Shimbun made the assessment after analyzing images North Korea disclosed late Tuesday of last Sunday’s rocket launch.

Quoting an official at the Japan Aerospace Exploration Agency, the paper said the orange flames and black smoke that resulted from the launch are similar to characteristics found in the burning of liquid hydrazine fuel, commonly use by China and Russia, adding that the North is unlikely to have used liquid hydrogen or liquid oxygen to fuel its rocket.

Asahi said if the North had used either liquid hydrogen or oxygen as fuel, the rocket would have produced white vapor upon launch.