(BSS/AFP) - President Donald Trump said Sunday that lethal strikes on small boats near the Venezuelan coast that US officials accuse of carrying drugs have been so successful "there are no boats" left in that area of the Caribbean.

"We`re stopping drugs at a level that nobody`s ever seen," Trump told a crowd of Navy sailors at the huge naval base Norfolk in Virginia.

"We`re so good at it that there are no boats. In fact, even fishing boats -- nobody wants to go into the water anymore. Sorry to tell you that," Trump said, chuckling. "We just can`t find any."

At least 21 people have been killed in the strikes so far, according to US officials.

The White House says the strikes, which have blown up at least four boats so far, are stopping drugs from reaching the United States.

However, Democrats and many legal experts question the legality of using lethal force in foreign or international waters against suspects who have not been intercepted or questioned.

Trump boasted that his policy was working and that military action could be expanded to land routes.

"They`re not coming in by sea anymore, so now we`ll have to start looking about the land, because they`ll be forced to go by land. And let me tell you right now, that`s not going to work out well for them either."

Trump referred to another deadly strike taking place "last night."

However the last one announced by the Pentagon was on Friday, when officials said they killed four unidentified people accused of being "narco-terrorists" on a small boat off Venezuela.

Video of the incident released by the Pentagon showed an open speedboat suddenly being engulfed in smoke and flames.