Panamanian officials have announced that they have detained and are searching a North Korean-flagged ship headed to North Korea from Cuba with suspected weapons onboard.

According to Panamanian President Ricardo Martinelli, the ship was carrying undeclared cargo hidden in containers under a cargo of sugar. The weapons appeared to be unconventional weapons and ballistic missiles. He released an image of some of the discovered cargo on Twitter. The image is believed to be of a suspected ballistic missile.

Only one of the vessel’s five holds have been searched as of Tuesday and the inspection continues.

Martinelli reported that his country was tipped of some days ago that the ship would be transiting the area and was suspected of carrying illegal cargo.

“This material not being declared and Panama being a neutral country, a country in peace, that doesn’t like war, we feel very worried about this war material and we don’t know what else will have … passed through the Panama Canal,” Martinelli said.

According to the Panamanian military, the crew resisted efforts to take the ship to the port of Manzanillo on the Caribbean side of Panama. The crew was later placed under arrest. The captain of the ship was reported to have had a heart attack and had also tried to kill himself during the search operation on the vessel.

The vessel, the Chong Chon Gang has long been suspected of such operations and has been caught running drugs and ammunition in the past. It first came under observation in 2009 when it was suspected of carrying illicit cargo after leaving the Syrian port of Tartus. That port hosts a Russian naval base.

Neither Cuba or North Korea has commented as yet of the seizure and search of the vessel.