Iran shares land borders with seven countries. Determining which one is "closest" depends on whether you are measuring by the length of the shared border or proximity to the Iranian capital, Tehran.

Here are the countries that share a land border with Iran:

• Iraq: Shares the longest border with Iran to the west.
• Pakistan: Shares a border to the southeast.
• Afghanistan: Shares a border to the east.
• Turkmenistan: Shares a border to the northeast.
• Azerbaijan: Shares a border to the northwest (includes the Nakhchivan exclave).
• Armenia: Shares a short border to the northwest.
• Turkey: Shares a border to the northwest.

Key considerations regarding proximity:

• By Border Proximity: If you are looking for the countries immediately adjacent to Iran, all seven listed above are equally "close" as they share a direct physical border.
• To Tehran: If you are measuring distance to the capital city, Iraq and Azerbaijan are geographically very close to the western and northwestern borders, while Turkmenistan is relatively close to the northern regions.
• Maritime Proximity: If you include maritime borders, countries like Kuwait, Saudi Arabia, Qatar, Bahrain, the United Arab Emirates, and Oman are also extremely close to Iran across the Persian Gulf and the Gulf of Oman.