IDF naval forces are preparing to intercept two vessels bound for Gaza in the latest attempt to breach Israel's blockade of the Hamas-run enclave.
The yachts - one Canadian and one Irish - departed Turkey on Wednesday carrying 27 anti-Israel activists.
Turkey denied it was aware the vessels intended to head for Gaza when they departed.
The activists on board the vessels are from Canada, the United States, Australia, the Palestinian Authority enclaves, and Ireland.
The IDF said it regarded the incident as a "provocation" but would not reveal how it intended to halt the yachts.
"We will have to wait to see if we are facing violent passengers," said military spokesman Lieutenant-Colonel Avital Leibovich.
Leibovich was referring to the Mavi Marmara incident in 2010, during which a mob of activists, mostly Turkish, attempted to lynch Israeli naval commandos who boarded the vessel.
When less-than-lethal means proved insufficient to protect their lives the commandos switched to live fire, killing 9 Turkish nationals.
A major flotilla of seventeen vessels planned for earlier in the year found itself scuttled by red tape in foreign ports, resulting in a lone vessel seeking to reach Gaza.
That vessel, a French yacht, was boarded by Israeli naval commandos without incident and redirected to the port of Ashdod.
Previously, Turkish Prime Minister Recep Tayyip Erdogan vowed to provide a Turkish naval escort for Gaza-bound vessels. According to observers, however, such an escort in this case is unlikely as neither ship is flying the Turkish flag.
Activists claim Israel's blockade of Gaza is collective punishment that has resulted in a humanitarian crisis.
Israeli officials, however, note the Kerem Shalom crossing between Gaza and Israel is never at full capacity despite all aid requests being met. As a result, they say, seeking to breach the blockade has nothing to do with humanitarian goals and only serves to undermine Israel's security.
During Ramadan, imams in Gaza launched a campaign to collect surplus aid goods to repackage and send to Somalia.
Earlier this year, noting the continued operation of the Kerem Shalom crossing, the UN Palmer committee concluded Israel's blockade is "legal and appropriate."
The IDF is expected to intercept the two ships near Gaza on Friday.