The Palestinian National Security Forces (NSF; Arabic: قوات الأمن الوطني الفلسطيني, romanized: Quwwat al-Amn al-Watani al-Filastini) are the paramilitary security forces of the Palestinian National Authority. The name may either refer to all National Security Forces, including some special services but not including the Interior Security Forces, the Presidential Guard and General Intelligence, or refer to the main force within the National Security Forces. Since the signing of the Oslo Accords, these forces operate in areas controlled by the PNA. In 2003, the organizations were merged into the Palestinian Security Services.

The Palestinian National Security Forces engage in various activities, including general law enforcement. A rough estimate of the total strength as of 2007 is 42,000 troops. As the Israeli-Palestinian conflict goes on, the security forces notably co-operate with other law enforcement agencies, such as arresting militant sub-groups and assisting the Israeli government with prosecuting those picked up. According to The Jerusalem Post, "In the past, Palestinian security forces have released arrested terrorists and then quietly tipped off Israel to mitigate internal public criticism against handing over Palestinians to Israel."

As part of the Oslo Accords, the Palestinian National Authority (PNA) was authorized to recruit and train a police force with paramilitary capabilities, but was not permitted to have a military force. Several bilateral agreements between the PNA and Israel regulate the size of the force, its structure, armament, and composition. The agreements provide Israel with the right to review potential recruits and withhold approval of those with a terrorist background. They were not enforced, however, with the result that the actual size and equipment of the force in 2002 exceeded what was permitted.

Initially, Yasser Arafat set up a string of 14 overlapping and often competing security forces, each one controlled by a rival political or former guerrilla chieftain, but all of them ultimately loyal to him and his Fatah party.

After Hamas had established a PNA government in March 2006, it formed its own security service, the Executive Force, headed by Jamal Abu Samhadana, who was killed by Israel three months later.

The National Security Forces engage in various activities, including general law enforcement. The Military Intelligence collects external military intelligence. It became the NSF Military Intelligence Department. The Military Police is a separate unit. The Military Liaison coordinates security with Israel and participated in joint Israeli–Palestinian patrols in the past. The Naval Police is tasked to protect the territorial waters of Gaza.

The predecessor of the NSF was the PLO's Palestine Liberation Army. When the NSF were formed, most personnel was recruited from the PLA. Gradually, local recruits were added.

From the late 1990s, the CIA played the central role in building up PA security forces, in close co-operation with the Israeli military and intelligence. After the killing of three US officials in the Gaza strip in 2003, British forces played an increasingly active role.