As the United States has unveiled their rigid sanctions with Iran in regards to their denuclearization, the world’s eyes are once again turned to the country to see how it will respond to financial threats. Sanctions coming from a country like the U.S. have historically been seen an alternative to real action to appease public opinion, but sanctions like this can have real, devastating effects — especially when coming from a consumer-heavy nation like America.

Many people think in different terms when it comes to the Middle East and its surrounding countries — some think in clusters. You’ve got the cluster of Saudi Arabia, Iraq and Iran all encroaching on Syria, Jordan and Israel. Eventually you have Turkey to the north. Then to the east, you have the Afghanistan and Pakistan cluster, and some might throw Turkmenistan and Uzbekistan in there too. Other people think in different groups — some may put Iran in a separate category altogether. Generations who are familiar with older conflicts might cluster other countries together in different combinations.

Whichever way it’s cut, the border of Iran and Afghanistan makes the news every so often, but the two are often not thought of as the direct neighbors that they are. They share almost 590 miles of border (945 km), and have a lot of controversial traffic that moves between them.

The U.S. presence in Afghanistan is right in Iran’s backdoor — this gives the U.S. a great strategic advantage in any aggression that may play out with Iran, much like the U.S. presence in South Korea as it relates to North Korea. This is the first obvious concern from the Iranian government as far as their poor U.S. relations go, but it goes deeper than that. The Afghan government is quite obviously in league with United States interests, and they are liable to enforce those interests even after the U.S. hypothetically pulls out. The Afghan government struggles with a lot of corruption, and whether or not they will withstand a U.S. withdrawal is up in the air, but the Iranian government is undoubtedly going to have concerns regarding a neighbor whose government was literally installed by their harshest international critic.

However, the U.S. presence next-door is not Iran’s only concern. Due to the war in Afghanistan, many fled the country to the west, seeking asylum in Iran. As Iran instated stricter immigration policies, their attitude toward Afghan immigrants began to change. In the 2010-2011 time frame, many Afghans were accused and charged with heinous crimes, such as rape and murder, and were publicly executed, causing an uproar among Afghans. Many were deported. They cut off certain exports to the country and the two have isolated themselves from one another ever since.

And as time has progressed, Iran has further concerned itself with the drugs coming in over the border. Afghanistan is, after all, the lead producer of opium in the world since the early 90s. They supply more than 90% of the world’s opium supply, and much of this goes through the western Afghan areas like Farah, Nimroz and Herat, right over the border into Iran. Despite the fact that the goal is to traffic these drugs through Iran to international suppliers, it has caused a huge drug problem in Iran — to the point where the U.N. considers Iran to have one of the worst drug problems in the world. An estimated 3 million people in Iran are addicted to hard substances, and that is out of a total population of approximately 80 million.

Iran has long publicly supported the Afghan government. After the Taliban were ousted from power, Iran’s trade with their neighbor increased exponentially, and despite their disdain for American influence, they have seemed to come out in support of the installed government. Imports and export businesses have thrived — millions of dollars in goods have played to the benefit of both countries.

With that said, many American officials have accused the Iranian government of playing nice externally while backhandedly supporting the Taliban. They have been accused of both training and funding the Taliban on more than one occasion.

For example, Gen. David Patraeus, who was the commander of U.S. and NATO forces in Afghanistan at the time, once told the Senate Armed Services Committee that,

We do see certainly Iranian activity to use both soft power in the way that they shut off the fuel going into Afghanistan a couple of months ago, and also certainly to influence the political process there as well in ways similar to what we saw in Iraq … We did interdict a shipment, without question the Revolutionary Guard’s core Quds Force, through a known Taliban facilitator. Three of the individuals were killed… 48 122 millimeter rockets were intercepted with their various components.”

To this end, Sen. Susan Collins said that, “Iranians certainly view as making life more difficult for us if Afghanistan is unstable.”

Two volatile, unstable countries like Iran and Afghanistan, who border one another and are in the center of some of the most complex geo-political conflicts in the world, are bound to have a tumultuous and unstable border.

Featured image: In this Nov. 17, 2007 file photo, Afghan border policemen view confiscated opium and alcoholic drinks on the outskirts of Herat city in Herat province, southwest of Kabul, Afghanistan. Iran is at the front lines of the war on drugs flowing from Afghanistan, stopping vast quantities of opium and heroin before they can reach western Europe, but Western nations including the United States recently warned Iran for the first time that it must halt a key part of its nuclear program to get any additional help fighting Afghan drug lords. (AP Photo/Fraidoon Pooyaa, File)