Israel was marking Memorial Day from sunset on Sunday, remembering fallen troops and civilian deaths in terror attacks.
Minute-long sirens sounded nationwide at 8.00 pm (1700 GMT), marking the beginning of the memorial day.
According to numbers published by the Defence Ministry, since the year 1860 -- when the first Jewish neighbourhood in Jerusalem outside of the Old City was founded and Israel considers the beginning of the Israel-Arab conflict -- 23,085 soldiers and members of the security forces died in the line of duty, including 92 in the past year.
An additional 2,493 civilians were killed in terror attacks in Israel and abroad since 1860, of them 10 in the past year, according to data from the Foreign Ministry.
"Since our inception as a people, we had to fight for our freedom and our existence," Prime Minister Benjamin Netanyahu said at a Sunday afternoon ceremony.
"Today, too, there are those who threaten to annihilate us -- they haven't succeeded in the past, they won't ever succeed", he said.
Netanyahu seemed to be alluding to Iran, which Israel believes is working toward achieving military nuclear capabilities and has issued bellicose statements against the Jewish state.
Last month, Iran's supreme leader Ayatollah Ali Khamenei said his country would "annihilate" the Israeli cities of Tel Aviv and Haifa if it comes under attack by the Jewish state.
In August, Khamenei said Israel will "disappear," while Iranian President Mahmoud Ahmadinejad has scorned the Jewish state as a "cancerous tumour".
"If we have no choice, we will grasp our swords and go to battle," Netanyahu said.
"We are not belligerent, we are not bloodthirsty. Our hand is extended in peace to all nations and states, far and near, but over the centuries we learned that only a strong defence force will ensure that we are not harmed."
Iran is said to possess ballistic missiles capable of reaching Israel. It also has close relations with Israel's foes in the region, including Lebanon's Hezbollah and Palestinian militants in the Islamist-ruled Gaza Strip.
Israel, widely believed to be the Middle East's sole but undeclared nuclear power, has not ruled out a military strike against Iran's nuclear facilities.
President Shimon Peres, speaking at a memorial service at the Western Wall in the Old City of Jerusalem, said that "Israel's existence is no longer in question. The IDF (Israel Defence Forces) is ready for any scenario, against any enemy."
Speaking after Peres, army chief Benny Gantz said that "if it seems that the enemy is no longer at our gate -- don't let that quiet mislead you," because "a storm of developing threats and dangers is raging below the surface."
The army imposed a general closure of the West Bank, beginning with the Sunday evening sirens and ending at midnight Tuesday, a statement read.
Israel regularly shuts down most traffic into and out of the West Bank during Jewish holidays, when the risk of attacks is perceived to be higher.
During the closure, Palestinians in the West Bank are only permitted to leave the territory in cases of urgent humanitarian need.
On Monday, further sirens will sound nationwide for two minutes at 11:00 am (0800 GMT), commencing ceremonies at dozens of cemeteries and military memorial sites across Israel.
Memorial Day is followed by Israel's Independence Day, marking 65 years since the declaration of statehood on May 14, 1948, which is celebrated according to the Jewish calendar and this year falls on April 16.
Palestinians mark the occasion on May 15, when they commemorate the Nakba, or "catastrophe" of the creation of Israel, which sparked the exodus of hundreds of thousands of Palestinians.