Europe’s gas price has risen to the highest level in four months as fighting between the United States and the Islamic Republic intensifies, increasing concerns about a winter supply shortage.

Based on a report by The Guardian, the Netherlands gas index temporarily rose above €60 per megawatt-hour on Monday, close to its peak since the start of the war. This increase followed the expansion of U.S. airstrikes and the Islamic Republic’s response with an attack on Bahrain and Kuwait.

Gas storage in Europe is now less than 54% full, compared with 64% in the same period last year.

Based on calculations by energy market analysis firm ICIS, since the start of the war, only 26 LNG shipments have left the Persian Gulf, whereas before the war, 90 to 100 shipments per month typically left the Persian Gulf.