Singapore Defence Minister Ng Eng Hen has warned Malaysian vessels to not encroach into Singaporean waters.
Ng claimed that "Malaysian government vessels" have been continually "intruding" waters at Tuas since November.
"These are serious violations of Singapore's sovereignty. Our security forces have acted with restraint despite continuing intrusions and provocations.
"Singaporeans are peace-loving, but I strongly caution violators to leave Singapore territorial waters," he wrote on his Facebook page this evening.
His Facebook post was accompanied with a video clip depicting RSS Independence issuing a warning to a Malaysian Marine Department vessel.
The video clip also depicted a Singapore Coast Guard vessel warning an unidentified vessel.
It ends with footages of RSS Independence, a coastal defence ship, and a caption stating that Singapore will not hesitate to take "firm action" against intrusions.
Singapore has accused Malaysia of altering port limits for the Johor Bahru Port in a way that has encroached waters off Tuas and that there were allegedly 14 intrusions thus far.
In a protest note to Putrajaya, Singapore had requested that Malaysia amend Gazette Notification PC 88/2018 and NtM 164/2018 to reflect the sovereignty of Singapore over the waters in question.
Prime Minister Dr Mahathir Mohamad has denied such allegations.