Israel has launched a construction project along the so-called Alpha Line, which marks the boundary between the Israeli-occupied Golan Heights and Syria.
Satellite images analyzed by The Associated Press (AP) reveal that asphalt is being laid for a road directly along the frontier.
Israeli troops have entered the demilitarized zone during the construction, a move confirmed by the United Nations, which described it as a violation of the cease-fire terms in the area.
The project, which satellite images show began in late September, follows the Israeli military's completion of new roads and a buffer zone along the Gaza Strip's border with Israel.
Meanwhile, Israel's military has also begun demolishing villages in Lebanon, where U.N. peacekeepers have recently come under fire.
Despite the construction, there has been no major violence along the Alpha Line, the demilitarized zone patrolled by U.N. peacekeepers since 1974.
Syria, which has been at war with Israel since its founding in 1948 and relies on Iran for support, has yet to comment on the development.
The Golan Heights remains a flashpoint for the two countries, making any changes along the border potentially even more sensitive.
The Israeli military did not respond to requests for comment, and Syrian officials in Damascus declined to comment.
High-resolution images taken on Nov. 5 by Planet Labs PBC for the AP show over 7.5 kilometers (4.6 miles) of construction along the Alpha Line, starting some 3 kilometers (1.8 miles) southeast of the Israeli-held Druze town of Majdal Shams, where a July rocket strike killed 12 children playing football.
The images appear to show a trench between two embankments, parts of which appear to have been laid with fresh asphalt.
There also appears to be fencing running along it toward the Syrian side.
The construction follows a southeast route before heading due south along the Alpha Line, then cutting southeast again.
The images show excavators and other earth-moving equipment actively digging along the route, with more asphalt piled there.
The area is also believed to be littered with unexploded ordnance and mines from decades of conflict.
The United Nations maintains a peacekeeping force in the demilitarized zone called the United Nations Disengagement Observer Force, or UNDOF.
"In recent months, UNDOF has observed construction activity being carried out by the IDF along the cease-fire line," U.N. peacekeeping spokesperson Nick Birnback told the AP, using an acronym for the Israeli military.
"In this regard, UNDOF has observed in some instances IDF personnel, Israeli excavators, other construction equipment, and the construction itself encroach into the area of separation."
Birnback added that "no military forces, equipment, or activity by either Israel or Syria are permitted in the area of separation."
While Israel hasn’t acknowledged the construction, it sent a 71-page letter in June to the U.N. outlining what it described as "Syrian violations of the Alpha Line and armed presence in the area of separation (that) occur daily." The letter cited numerous Israeli-alleged violations by Syrian civilians crossing the line.
"Syrian violations of that agreement only heighten tensions in our already volatile region," the letter added.
Syria has repeatedly accused Israel of launching attacks from territory it occupies in the Golan Heights.
Israel has repeatedly struck Syria over the years, particularly after the start of the latest Mideast conflicts following Hamas’ Oct. 7, 2023, incursion on southern Israel.
Israel seized control of the Golan Heights from Syria in the 1967 Mideast war. After the 1973 Mideast war, the U.N. Security Council voted to create UNDOF to patrol a roughly 400-square-kilometer (155-square-mile) demilitarized zone and maintain the peace there.
A second demarcation, known as the Bravo Line, marks the limit of where the Syrian military can operate.
UNDOF has about 1,100 troops, mostly from Fiji, India, Kazakhstan, Nepal, and Uruguay, who patrol the area.
Israel annexed the Golan Heights in 1981 – a move criticized by a U.N. resolution declaring Israel’s action as "null and void and without international legal effect." The territory, about 1,200 square kilometers (460 square miles) in size, is a strategic high ground that overlooks both Israel and Syria.
The population of around 50,000 includes Jewish settlers and Arabs, mostly members of the Druze sect of Shiite Islam.
In 2019, President Donald Trump unilaterally announced that the U.S. would "fully recognize" Israel’s control of the territory, a decision that has been unchanged by the Biden administration.