Mexico–United States barrier in the context of "San Diego"

The Egypt–Israel barrier or Egypt–Israel border fence (Hebrew: שְׁעוֹן הַחוֹל, romanized: Sheʽon HaḤol, lit. 'sand clock') refers to a separation barrier built by Israel along its border with Egypt. Initial construction on the barrier began on 22 November 2010, and its original purpose as a common fence was to curb the large influx of illegal migrants from African countries into Israel. However, in the wake of the Egyptian Crisis after the 2011 Revolution, Israel's southwestern border with Egypt experienced an increase in militant jihadist activity with the outbreak of the Sinai insurgency. In response, Israel upgraded the steel barrier—called Project Hourglass by the Israel Defense Forces (IDF)—to include cameras, radars, and motion detectors. In January 2013, construction on the barrier's main section was completed; the final section was completed in December 2013.

A number of countries, including the United States and India, have sent delegations to Israel to observe its border-controlling capabilities and the various technologies used by the IDF to secure Israel's boundaries against the Arab states. Some of these countries have expressed an interest in implementing Israeli strategies and technologies with their own border fences; the Trump administration cited Israel's border strategies as inspiration for the barrier built by the United States along its border with Mexico, while Indian officials have discussed the implementation of an "Israel-type model" for the barrier built by India along its border with Pakistan.

A border barrier, border fence or border wall is a separation barrier that runs along or near an international border. Such barriers are typically constructed for border control purposes such as curbing illegal immigration, human trafficking, and smuggling. Some such barriers are constructed for defence or security reasons. In cases of a disputed or unclear border, erecting a barrier can serve as a de facto unilateral consolidation of a territorial claim that can supersede formal delimitation. A border barrier does not usually indicate the location of the actual border, and is usually constructed unilaterally by a country, without the agreement or cooperation of the other country.

Examples of border walls include the ancient Great Wall of China, a series of walls separating China from nomadic empires to the north. The construction of border barriers increased in the early 2000s; half of all the border barriers built since World War II, which ended in 1945, were built after 2000.