Ceasefires, Proportionality, and International Law of Armed Conflicts: The Legal Implications of Israel’s Ground Invasion After Signing a Ceasefire with Palestine

Photo by Matthias Redding via Unsplash

Israel signed a ceasefire with Palestine on January 17, 2025,[1] after 15 months of war following Hamas’ attack on Israel on October 7, 2023.[2] During the initial attack, Hamas killed more than 1,200 people and seized 251 Israeli hostages.[3] A key part of the ceasefire involved the return of these hostages.

The ceasefire took a phased approach. It began with an initial 6-week cessation of hostilities with room for extension. Importantly, Israel did not agree to a full withdrawal and included conditions for continuing into the later phases of the cessation, including the release of hostages.

The ceasefire was extended for over two months, during which time Hamas released 33 Israeli hostages, and Israel released approximately 1,900 Palestinian prisoners. [4] Additionally, humanitarian aid finally resumed in Gaza, with aid trucks able to reenter to provide supplies and help facilitate the return of Palestinians to northern Gaza.[5]From the beginning, however, there were accusations that Israel was obstructing and violating the ceasefire by continuing aggression and hindering aid.[6] Similarly, Israel accused Hamas of violating the deal by delaying hostage release and not being honest in the identities of bodies being returned to Israel.[7]

As per the Geneva Conventions, the central international protocol governing the law of armed international conflict (or International Humanitarian law, IHL), parties to ceasefires must act in good faith.[8] This principle is strengthened by the Vienna Convention on the Law of Treaties, which states that all international agreements must be performed in good faith.[9] Another foundational principle of IHL is proportionality and military necessity. Under Article 51(5)(b) of Additional Protocol I to the Geneva Convention, attacks are prohibited that cause excessive “loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof” in relation to the anticipated military advantage.[10]

While one could argue that Hamas violated good faith principles by not completing their end of the agreement in releasing all hostages, I argue that Israel’s invasion was a disproportionate reaction that threatened to reverse the humanitarian progress achieved over the last two months and put more civilians at risk than necessary to apply the pressure Israel sought to get Hamas to release the remaining hostages. It has been reported that Israel’s initial airstrikes alone killed more than 400 Palestinians.[11] The number of civilians killed far outweighs the number of Israeli hostages yet to be released by Hamas.

However, proportionality is not measured by looking simply at a one-to-one balance of life-for-life. The principle of proportionality involves balancing military necessity with humanitarian concerns. Israel could argue that the military advantage they calculated by creating pressure from these attacks may have not been “in excess” by their calculations. Still, this could be challenged and is complicated by Article 51 and 57 of the Additional Protocol I to the Geneva Conventions which requires that military actions be “concrete and direct” toward achieving some military advantage, and the death of 400 Palestinians does not on its face seem concrete and direct if the aims of the attack were to target Hamas.[12]

Importantly, there were other methods Israel could have used to pressure Hamas to release the remaining hostages other than escalating to a deadly attack, such as: increasing diplomatic efforts through international mediators in the region, like Saudi Arabia, Turkey, or Egypt; adjusting the terms of the remaining hostage release and make it dependent on Hamas’s cooperation with more a rigid timeline; or bring a claim against Hamas with a multilateral governing body, such as the UN or ICJ.

In conclusion Israel’s resumption of hostilities, not only through airstrikes but occupation via ground invasion raises significant questions about the potential violations Israel may have made in breaking their promises under the ceasefire. This case highlights the need for a stronger international framework for ceasefires to ensure more robust protection for civilians and mechanisms to avoid unnecessary casualties while ensuring the best success for long-term peace.

Emma Lee is a Staff Editor at CICLR.

[1] The agreement between Hamas and Israel was reached on January 17, 2025, and went into effect on January 19, 2025. Aaron Boxerman, Israeli Government Approves Gaza Cease-Fire, N.Y. Times (Jan 17, 2025), https://www.nytimes.com/live/2025/01/17/world/israel-hamas-gaza-ceasefire [https://perma.cc/EF2R-JVDN].

[2]Jeremy M. Sharp & Jim Zanotti, Israel and Hamas Conflict in Brief:Overview, U.S. Policy, and Options for Congress, Cong. Rsch. Serv. (Mar. 5, 2024), https://www.congress.gov/crs-product/R47828 [https://perma.cc/R8B6-FWQT].

[3] Id.

[4] Anas Baba, Daniel Estrin, Katy Lonsdorf, Israel Declares Ceasefire ‘Over’ As It Launches Airstrikes In Gaza Killing Hundreds, Nat’l Pub. Radio (Mar. 18, 2025) https://www.npr.org/2025/03/17/g-s1-54401/israel-launches-deadly-series-of-attack-on-gaza [https://perma.cc/97VZ-84K2].

[5] Id.

[6] Lyndal Rowlands, Umut Uras, Maziar Motamedi, Alice Speri & Urooba Jamal, Updates: Hamas suspends captive release citing Israel’s truce violations, Al Jazeera (Feb. 10, 2025), https://www.aljazeera.com/news/liveblog/2025/2/10/live-israeli-forces-kill-6-in-gaza-west-bank-as-trump-repeats-gaza-plan?update=3501117 [https://perma.cc/F3EA-VXF9].

[7] The Times of Israel, Hamas has failed to provide Israel list with status of hostages to be freed

(Jan. 26, 2025), https://www.timesofisrael.com/liveblog_entry/hamas-has-failed-to-provide-israel-list-with-status-of-hostages-to-be-freed/[https://perma.cc/P2GZ-4A5X].

[8] Although the Geneva Conventions do not explicitly mention “good faith,” it is inherent in states obligations. For example, Common Article 1 of the 1949 Geneva Conventions states: "The High Contracting Parties undertake to respect and to ensure respect for the present Convention in all circumstances." 6 U.S.T. 3114 (Aug. 12, 1949).

[9]  Vienna Convention on the Law of Treaties, May 23, 1969, 1155 U.N.T.S. 331, Art. 26 (defining “pacta sunt servanda”).

[10] Protocols Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I) (hereinafter "Protocols), Int’l Comm. Red Cross, Art. 51(5)(b) (June 8, 1977), https://www.icrc.org/sites/default/files/external/doc/en/assets/files/other/icrc_002_0321.pdf [https://perma.cc/QH6U-EQ6Q].

[11] James Mackenzie, Nidal Al-Mughrabi & Emily Rose, Israel Warns More To Come As Airstrikes Kill Over 400 In Gaza After Two Months Of Truce, Reuters (Mar. 18, 2025), https://www.reuters.com/world/middle-east/israeli-military-conducts-strikes-hamas-targets-gaza-army-says-2025-03-18/ [https://perma.cc/P3JT-3VD5].

[12] Protocols, supra note 10.